Why does ${-}14 bmod 12 = 10$?
$begingroup$
Why does $-14 bmod 12 = 10$?
I would be grateful if someone could explain this to me step by step, for I am but a novice in the field of modular arithmetic.
Thank you!
Edit: I would like to hit myself on the head- I see it now. Thanks to everyone who responded!
elementary-number-theory modular-arithmetic
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lєαf is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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show 1 more comment
$begingroup$
Why does $-14 bmod 12 = 10$?
I would be grateful if someone could explain this to me step by step, for I am but a novice in the field of modular arithmetic.
Thank you!
Edit: I would like to hit myself on the head- I see it now. Thanks to everyone who responded!
elementary-number-theory modular-arithmetic
New contributor
lєαf is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
$begingroup$
I think it's the latter, but that wouldn't make much sense here. I was playing around with the google calculator when I came up with this equation.
$endgroup$
– lєαf
2 hours ago
$begingroup$
@GunnarSveinsson : I would downvote your comment if I could. There is one and only one sane definition of $a mod n$ (where $n>0$). It is the unique value in $[0,n)$ which can be obtained by adding an integral multiple of $n$ to $a$.
$endgroup$
– MPW
2 hours ago
$begingroup$
@MPW It is true that the first definition / notation is wrong, but it is not true that there is only one definition of operational mod, e.g. it might denote the canonical residue in a system of least magnitude reps, e.g. $, -1,0,1pmod{3}. $ Its definition is relative to the complete system of reps employed.
$endgroup$
– Bill Dubuque
2 hours ago
$begingroup$
@MPW: Taking the latter definition gives you a function that isn't additive (i.e., $text{mod}(a+b, n) not= text{mod}(a, n) + text{mod}(b, n)$ in general, isn't multiplicative, may have strange behavior with negative arguments, and doesn't easily generalize outside the integers. It's convenient in some settings (e.g., programming) to recast $text{mod}$ a function rather than an equivalence relation by taking a single representative of the equivalence class under it, but it's often the far less sane choice.
$endgroup$
– anomaly
1 hour ago
1
$begingroup$
@anomaly : I think of ‘mod’ as giving the representative in the base coset
$endgroup$
– MPW
53 mins ago
|
show 1 more comment
$begingroup$
Why does $-14 bmod 12 = 10$?
I would be grateful if someone could explain this to me step by step, for I am but a novice in the field of modular arithmetic.
Thank you!
Edit: I would like to hit myself on the head- I see it now. Thanks to everyone who responded!
elementary-number-theory modular-arithmetic
New contributor
lєαf is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
Why does $-14 bmod 12 = 10$?
I would be grateful if someone could explain this to me step by step, for I am but a novice in the field of modular arithmetic.
Thank you!
Edit: I would like to hit myself on the head- I see it now. Thanks to everyone who responded!
elementary-number-theory modular-arithmetic
elementary-number-theory modular-arithmetic
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lєαf is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
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edited 1 hour ago
Bill Dubuque
210k29192640
210k29192640
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asked 2 hours ago
lєαflєαf
43
43
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$begingroup$
I think it's the latter, but that wouldn't make much sense here. I was playing around with the google calculator when I came up with this equation.
$endgroup$
– lєαf
2 hours ago
$begingroup$
@GunnarSveinsson : I would downvote your comment if I could. There is one and only one sane definition of $a mod n$ (where $n>0$). It is the unique value in $[0,n)$ which can be obtained by adding an integral multiple of $n$ to $a$.
$endgroup$
– MPW
2 hours ago
$begingroup$
@MPW It is true that the first definition / notation is wrong, but it is not true that there is only one definition of operational mod, e.g. it might denote the canonical residue in a system of least magnitude reps, e.g. $, -1,0,1pmod{3}. $ Its definition is relative to the complete system of reps employed.
$endgroup$
– Bill Dubuque
2 hours ago
$begingroup$
@MPW: Taking the latter definition gives you a function that isn't additive (i.e., $text{mod}(a+b, n) not= text{mod}(a, n) + text{mod}(b, n)$ in general, isn't multiplicative, may have strange behavior with negative arguments, and doesn't easily generalize outside the integers. It's convenient in some settings (e.g., programming) to recast $text{mod}$ a function rather than an equivalence relation by taking a single representative of the equivalence class under it, but it's often the far less sane choice.
$endgroup$
– anomaly
1 hour ago
1
$begingroup$
@anomaly : I think of ‘mod’ as giving the representative in the base coset
$endgroup$
– MPW
53 mins ago
|
show 1 more comment
$begingroup$
I think it's the latter, but that wouldn't make much sense here. I was playing around with the google calculator when I came up with this equation.
$endgroup$
– lєαf
2 hours ago
$begingroup$
@GunnarSveinsson : I would downvote your comment if I could. There is one and only one sane definition of $a mod n$ (where $n>0$). It is the unique value in $[0,n)$ which can be obtained by adding an integral multiple of $n$ to $a$.
$endgroup$
– MPW
2 hours ago
$begingroup$
@MPW It is true that the first definition / notation is wrong, but it is not true that there is only one definition of operational mod, e.g. it might denote the canonical residue in a system of least magnitude reps, e.g. $, -1,0,1pmod{3}. $ Its definition is relative to the complete system of reps employed.
$endgroup$
– Bill Dubuque
2 hours ago
$begingroup$
@MPW: Taking the latter definition gives you a function that isn't additive (i.e., $text{mod}(a+b, n) not= text{mod}(a, n) + text{mod}(b, n)$ in general, isn't multiplicative, may have strange behavior with negative arguments, and doesn't easily generalize outside the integers. It's convenient in some settings (e.g., programming) to recast $text{mod}$ a function rather than an equivalence relation by taking a single representative of the equivalence class under it, but it's often the far less sane choice.
$endgroup$
– anomaly
1 hour ago
1
$begingroup$
@anomaly : I think of ‘mod’ as giving the representative in the base coset
$endgroup$
– MPW
53 mins ago
$begingroup$
I think it's the latter, but that wouldn't make much sense here. I was playing around with the google calculator when I came up with this equation.
$endgroup$
– lєαf
2 hours ago
$begingroup$
I think it's the latter, but that wouldn't make much sense here. I was playing around with the google calculator when I came up with this equation.
$endgroup$
– lєαf
2 hours ago
$begingroup$
@GunnarSveinsson : I would downvote your comment if I could. There is one and only one sane definition of $a mod n$ (where $n>0$). It is the unique value in $[0,n)$ which can be obtained by adding an integral multiple of $n$ to $a$.
$endgroup$
– MPW
2 hours ago
$begingroup$
@GunnarSveinsson : I would downvote your comment if I could. There is one and only one sane definition of $a mod n$ (where $n>0$). It is the unique value in $[0,n)$ which can be obtained by adding an integral multiple of $n$ to $a$.
$endgroup$
– MPW
2 hours ago
$begingroup$
@MPW It is true that the first definition / notation is wrong, but it is not true that there is only one definition of operational mod, e.g. it might denote the canonical residue in a system of least magnitude reps, e.g. $, -1,0,1pmod{3}. $ Its definition is relative to the complete system of reps employed.
$endgroup$
– Bill Dubuque
2 hours ago
$begingroup$
@MPW It is true that the first definition / notation is wrong, but it is not true that there is only one definition of operational mod, e.g. it might denote the canonical residue in a system of least magnitude reps, e.g. $, -1,0,1pmod{3}. $ Its definition is relative to the complete system of reps employed.
$endgroup$
– Bill Dubuque
2 hours ago
$begingroup$
@MPW: Taking the latter definition gives you a function that isn't additive (i.e., $text{mod}(a+b, n) not= text{mod}(a, n) + text{mod}(b, n)$ in general, isn't multiplicative, may have strange behavior with negative arguments, and doesn't easily generalize outside the integers. It's convenient in some settings (e.g., programming) to recast $text{mod}$ a function rather than an equivalence relation by taking a single representative of the equivalence class under it, but it's often the far less sane choice.
$endgroup$
– anomaly
1 hour ago
$begingroup$
@MPW: Taking the latter definition gives you a function that isn't additive (i.e., $text{mod}(a+b, n) not= text{mod}(a, n) + text{mod}(b, n)$ in general, isn't multiplicative, may have strange behavior with negative arguments, and doesn't easily generalize outside the integers. It's convenient in some settings (e.g., programming) to recast $text{mod}$ a function rather than an equivalence relation by taking a single representative of the equivalence class under it, but it's often the far less sane choice.
$endgroup$
– anomaly
1 hour ago
1
1
$begingroup$
@anomaly : I think of ‘mod’ as giving the representative in the base coset
$endgroup$
– MPW
53 mins ago
$begingroup$
@anomaly : I think of ‘mod’ as giving the representative in the base coset
$endgroup$
– MPW
53 mins ago
|
show 1 more comment
7 Answers
7
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votes
$begingroup$
$-14equiv10pmod{12},$ because $,{-}14=10-12cdot 2$. In other words, $-14$ and $10$ leaves the same remainder after dividing $12.$
$endgroup$
1
$begingroup$
The notation means not only they are congruent but, further that $10$ is the canonical rep from the equivalence class $,-14+12Bbb Z,$ wrt the complete system of residues $bmod 12,$ that one is using.
$endgroup$
– Bill Dubuque
1 hour ago
add a comment |
$begingroup$
14 hours before midnight, it's 10 o'clock.
$endgroup$
2
$begingroup$
Best possible answer. +1.
$endgroup$
– MPW
2 hours ago
add a comment |
$begingroup$
-24 is the largest number less than -14 which is congruent to 0 mod 12. -24 + 10 = -14 so -14 = 10 mod 12.
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add a comment |
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Because $10 -(-14) = 24$ which is a multiple of 12. In general, $ aequiv b pmod m $ means that $m$ divides $a-b$.
$endgroup$
add a comment |
$begingroup$
If you have $atext{ mod }b = c$ then there exists $kinmathbb Z$ such that $a=kb+c$. In your case, you have $a=-14$, $b=12$ and $c=10$ while $k=-2$:
$$
-14 = -2cdot 12+10.
$$
$endgroup$
add a comment |
$begingroup$
I know it's tempting to think of mod as an operation, but most often in modular arithmetic, it's a modifier of $equiv$, specifying exactly what "congruence" means. Really, if the notation had been $-14equiv_{12}10$ instead, this would've been so much clearer.
So $-14mod 12$ doesn't mean anything. On the other hand, $-14equiv10mod12$ is a statement. We can check whether it's true by using the definition:
$$
aequiv bmod ciff cmid a-b
$$
In this case, we get $12mid -14-10$, which is true. This means that $-14equiv 10mod 12$ is true.
$endgroup$
1
$begingroup$
I disagree that $-14 mod 12$ doesn't mean anything. I have seen this been treated as the image of $-14$ under the function $mod 12 : mathbb{Z}to mathbb{Z}$ or even of the canonical function $ mathbb{Z}to mathbb{Z}/12mathbb{Z}$. In a computer science course I took this expression was treated as a number.
$endgroup$
– Gunnar Sveinsson
2 hours ago
$begingroup$
Although if "modular aritmetic" is more well defined than I think, you may be right that it doesnt really mean anything in that "field".
$endgroup$
– Gunnar Sveinsson
2 hours ago
1
$begingroup$
The operation $bmod$ is certainly in wide use in mathematics, computer science, etc. So it is incorrect and misleading to claim the it "doesn't mean anything".
$endgroup$
– Bill Dubuque
2 hours ago
$begingroup$
@BillDubuque I tried to make it clear that I'm talking in the context of modular arithmetic.
$endgroup$
– Arthur
1 hour ago
$begingroup$
@Arthur And so am I.
$endgroup$
– Bill Dubuque
1 hour ago
add a comment |
$begingroup$
Whenever you get a positive number, you remove $12$ until you get a number between $0$ And $11$ to get the modulo.
Example: $ 37bmod{12}equiv 37-12equiv 25equiv 25-12equiv 13equiv 13-12equiv 1pmod{12}$
For a negative number, in the same way just add $12$ until you get something positive.
Example: $ {-}14bmod{12}equiv -14+12equiv -2equiv -2+12equiv 10pmod{12}$
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add a comment |
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7 Answers
7
active
oldest
votes
7 Answers
7
active
oldest
votes
active
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active
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votes
$begingroup$
$-14equiv10pmod{12},$ because $,{-}14=10-12cdot 2$. In other words, $-14$ and $10$ leaves the same remainder after dividing $12.$
$endgroup$
1
$begingroup$
The notation means not only they are congruent but, further that $10$ is the canonical rep from the equivalence class $,-14+12Bbb Z,$ wrt the complete system of residues $bmod 12,$ that one is using.
$endgroup$
– Bill Dubuque
1 hour ago
add a comment |
$begingroup$
$-14equiv10pmod{12},$ because $,{-}14=10-12cdot 2$. In other words, $-14$ and $10$ leaves the same remainder after dividing $12.$
$endgroup$
1
$begingroup$
The notation means not only they are congruent but, further that $10$ is the canonical rep from the equivalence class $,-14+12Bbb Z,$ wrt the complete system of residues $bmod 12,$ that one is using.
$endgroup$
– Bill Dubuque
1 hour ago
add a comment |
$begingroup$
$-14equiv10pmod{12},$ because $,{-}14=10-12cdot 2$. In other words, $-14$ and $10$ leaves the same remainder after dividing $12.$
$endgroup$
$-14equiv10pmod{12},$ because $,{-}14=10-12cdot 2$. In other words, $-14$ and $10$ leaves the same remainder after dividing $12.$
edited 2 hours ago
MPW
29.9k12056
29.9k12056
answered 2 hours ago
abc...abc...
2,820635
2,820635
1
$begingroup$
The notation means not only they are congruent but, further that $10$ is the canonical rep from the equivalence class $,-14+12Bbb Z,$ wrt the complete system of residues $bmod 12,$ that one is using.
$endgroup$
– Bill Dubuque
1 hour ago
add a comment |
1
$begingroup$
The notation means not only they are congruent but, further that $10$ is the canonical rep from the equivalence class $,-14+12Bbb Z,$ wrt the complete system of residues $bmod 12,$ that one is using.
$endgroup$
– Bill Dubuque
1 hour ago
1
1
$begingroup$
The notation means not only they are congruent but, further that $10$ is the canonical rep from the equivalence class $,-14+12Bbb Z,$ wrt the complete system of residues $bmod 12,$ that one is using.
$endgroup$
– Bill Dubuque
1 hour ago
$begingroup$
The notation means not only they are congruent but, further that $10$ is the canonical rep from the equivalence class $,-14+12Bbb Z,$ wrt the complete system of residues $bmod 12,$ that one is using.
$endgroup$
– Bill Dubuque
1 hour ago
add a comment |
$begingroup$
14 hours before midnight, it's 10 o'clock.
$endgroup$
2
$begingroup$
Best possible answer. +1.
$endgroup$
– MPW
2 hours ago
add a comment |
$begingroup$
14 hours before midnight, it's 10 o'clock.
$endgroup$
2
$begingroup$
Best possible answer. +1.
$endgroup$
– MPW
2 hours ago
add a comment |
$begingroup$
14 hours before midnight, it's 10 o'clock.
$endgroup$
14 hours before midnight, it's 10 o'clock.
answered 2 hours ago
orionorion
13.5k11837
13.5k11837
2
$begingroup$
Best possible answer. +1.
$endgroup$
– MPW
2 hours ago
add a comment |
2
$begingroup$
Best possible answer. +1.
$endgroup$
– MPW
2 hours ago
2
2
$begingroup$
Best possible answer. +1.
$endgroup$
– MPW
2 hours ago
$begingroup$
Best possible answer. +1.
$endgroup$
– MPW
2 hours ago
add a comment |
$begingroup$
-24 is the largest number less than -14 which is congruent to 0 mod 12. -24 + 10 = -14 so -14 = 10 mod 12.
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add a comment |
$begingroup$
-24 is the largest number less than -14 which is congruent to 0 mod 12. -24 + 10 = -14 so -14 = 10 mod 12.
New contributor
Sonechka is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
add a comment |
$begingroup$
-24 is the largest number less than -14 which is congruent to 0 mod 12. -24 + 10 = -14 so -14 = 10 mod 12.
New contributor
Sonechka is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
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-24 is the largest number less than -14 which is congruent to 0 mod 12. -24 + 10 = -14 so -14 = 10 mod 12.
New contributor
Sonechka is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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answered 2 hours ago
SonechkaSonechka
212
212
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add a comment |
add a comment |
$begingroup$
Because $10 -(-14) = 24$ which is a multiple of 12. In general, $ aequiv b pmod m $ means that $m$ divides $a-b$.
$endgroup$
add a comment |
$begingroup$
Because $10 -(-14) = 24$ which is a multiple of 12. In general, $ aequiv b pmod m $ means that $m$ divides $a-b$.
$endgroup$
add a comment |
$begingroup$
Because $10 -(-14) = 24$ which is a multiple of 12. In general, $ aequiv b pmod m $ means that $m$ divides $a-b$.
$endgroup$
Because $10 -(-14) = 24$ which is a multiple of 12. In general, $ aequiv b pmod m $ means that $m$ divides $a-b$.
edited 2 hours ago
Bill Dubuque
210k29192640
210k29192640
answered 2 hours ago
NickDNickD
1,0921412
1,0921412
add a comment |
add a comment |
$begingroup$
If you have $atext{ mod }b = c$ then there exists $kinmathbb Z$ such that $a=kb+c$. In your case, you have $a=-14$, $b=12$ and $c=10$ while $k=-2$:
$$
-14 = -2cdot 12+10.
$$
$endgroup$
add a comment |
$begingroup$
If you have $atext{ mod }b = c$ then there exists $kinmathbb Z$ such that $a=kb+c$. In your case, you have $a=-14$, $b=12$ and $c=10$ while $k=-2$:
$$
-14 = -2cdot 12+10.
$$
$endgroup$
add a comment |
$begingroup$
If you have $atext{ mod }b = c$ then there exists $kinmathbb Z$ such that $a=kb+c$. In your case, you have $a=-14$, $b=12$ and $c=10$ while $k=-2$:
$$
-14 = -2cdot 12+10.
$$
$endgroup$
If you have $atext{ mod }b = c$ then there exists $kinmathbb Z$ such that $a=kb+c$. In your case, you have $a=-14$, $b=12$ and $c=10$ while $k=-2$:
$$
-14 = -2cdot 12+10.
$$
answered 2 hours ago
Mundron SchmidtMundron Schmidt
7,3942729
7,3942729
add a comment |
add a comment |
$begingroup$
I know it's tempting to think of mod as an operation, but most often in modular arithmetic, it's a modifier of $equiv$, specifying exactly what "congruence" means. Really, if the notation had been $-14equiv_{12}10$ instead, this would've been so much clearer.
So $-14mod 12$ doesn't mean anything. On the other hand, $-14equiv10mod12$ is a statement. We can check whether it's true by using the definition:
$$
aequiv bmod ciff cmid a-b
$$
In this case, we get $12mid -14-10$, which is true. This means that $-14equiv 10mod 12$ is true.
$endgroup$
1
$begingroup$
I disagree that $-14 mod 12$ doesn't mean anything. I have seen this been treated as the image of $-14$ under the function $mod 12 : mathbb{Z}to mathbb{Z}$ or even of the canonical function $ mathbb{Z}to mathbb{Z}/12mathbb{Z}$. In a computer science course I took this expression was treated as a number.
$endgroup$
– Gunnar Sveinsson
2 hours ago
$begingroup$
Although if "modular aritmetic" is more well defined than I think, you may be right that it doesnt really mean anything in that "field".
$endgroup$
– Gunnar Sveinsson
2 hours ago
1
$begingroup$
The operation $bmod$ is certainly in wide use in mathematics, computer science, etc. So it is incorrect and misleading to claim the it "doesn't mean anything".
$endgroup$
– Bill Dubuque
2 hours ago
$begingroup$
@BillDubuque I tried to make it clear that I'm talking in the context of modular arithmetic.
$endgroup$
– Arthur
1 hour ago
$begingroup$
@Arthur And so am I.
$endgroup$
– Bill Dubuque
1 hour ago
add a comment |
$begingroup$
I know it's tempting to think of mod as an operation, but most often in modular arithmetic, it's a modifier of $equiv$, specifying exactly what "congruence" means. Really, if the notation had been $-14equiv_{12}10$ instead, this would've been so much clearer.
So $-14mod 12$ doesn't mean anything. On the other hand, $-14equiv10mod12$ is a statement. We can check whether it's true by using the definition:
$$
aequiv bmod ciff cmid a-b
$$
In this case, we get $12mid -14-10$, which is true. This means that $-14equiv 10mod 12$ is true.
$endgroup$
1
$begingroup$
I disagree that $-14 mod 12$ doesn't mean anything. I have seen this been treated as the image of $-14$ under the function $mod 12 : mathbb{Z}to mathbb{Z}$ or even of the canonical function $ mathbb{Z}to mathbb{Z}/12mathbb{Z}$. In a computer science course I took this expression was treated as a number.
$endgroup$
– Gunnar Sveinsson
2 hours ago
$begingroup$
Although if "modular aritmetic" is more well defined than I think, you may be right that it doesnt really mean anything in that "field".
$endgroup$
– Gunnar Sveinsson
2 hours ago
1
$begingroup$
The operation $bmod$ is certainly in wide use in mathematics, computer science, etc. So it is incorrect and misleading to claim the it "doesn't mean anything".
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– Bill Dubuque
2 hours ago
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@BillDubuque I tried to make it clear that I'm talking in the context of modular arithmetic.
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– Arthur
1 hour ago
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@Arthur And so am I.
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– Bill Dubuque
1 hour ago
add a comment |
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I know it's tempting to think of mod as an operation, but most often in modular arithmetic, it's a modifier of $equiv$, specifying exactly what "congruence" means. Really, if the notation had been $-14equiv_{12}10$ instead, this would've been so much clearer.
So $-14mod 12$ doesn't mean anything. On the other hand, $-14equiv10mod12$ is a statement. We can check whether it's true by using the definition:
$$
aequiv bmod ciff cmid a-b
$$
In this case, we get $12mid -14-10$, which is true. This means that $-14equiv 10mod 12$ is true.
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I know it's tempting to think of mod as an operation, but most often in modular arithmetic, it's a modifier of $equiv$, specifying exactly what "congruence" means. Really, if the notation had been $-14equiv_{12}10$ instead, this would've been so much clearer.
So $-14mod 12$ doesn't mean anything. On the other hand, $-14equiv10mod12$ is a statement. We can check whether it's true by using the definition:
$$
aequiv bmod ciff cmid a-b
$$
In this case, we get $12mid -14-10$, which is true. This means that $-14equiv 10mod 12$ is true.
edited 2 hours ago
answered 2 hours ago
ArthurArthur
113k7115197
113k7115197
1
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I disagree that $-14 mod 12$ doesn't mean anything. I have seen this been treated as the image of $-14$ under the function $mod 12 : mathbb{Z}to mathbb{Z}$ or even of the canonical function $ mathbb{Z}to mathbb{Z}/12mathbb{Z}$. In a computer science course I took this expression was treated as a number.
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– Gunnar Sveinsson
2 hours ago
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Although if "modular aritmetic" is more well defined than I think, you may be right that it doesnt really mean anything in that "field".
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– Gunnar Sveinsson
2 hours ago
1
$begingroup$
The operation $bmod$ is certainly in wide use in mathematics, computer science, etc. So it is incorrect and misleading to claim the it "doesn't mean anything".
$endgroup$
– Bill Dubuque
2 hours ago
$begingroup$
@BillDubuque I tried to make it clear that I'm talking in the context of modular arithmetic.
$endgroup$
– Arthur
1 hour ago
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@Arthur And so am I.
$endgroup$
– Bill Dubuque
1 hour ago
add a comment |
1
$begingroup$
I disagree that $-14 mod 12$ doesn't mean anything. I have seen this been treated as the image of $-14$ under the function $mod 12 : mathbb{Z}to mathbb{Z}$ or even of the canonical function $ mathbb{Z}to mathbb{Z}/12mathbb{Z}$. In a computer science course I took this expression was treated as a number.
$endgroup$
– Gunnar Sveinsson
2 hours ago
$begingroup$
Although if "modular aritmetic" is more well defined than I think, you may be right that it doesnt really mean anything in that "field".
$endgroup$
– Gunnar Sveinsson
2 hours ago
1
$begingroup$
The operation $bmod$ is certainly in wide use in mathematics, computer science, etc. So it is incorrect and misleading to claim the it "doesn't mean anything".
$endgroup$
– Bill Dubuque
2 hours ago
$begingroup$
@BillDubuque I tried to make it clear that I'm talking in the context of modular arithmetic.
$endgroup$
– Arthur
1 hour ago
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@Arthur And so am I.
$endgroup$
– Bill Dubuque
1 hour ago
1
1
$begingroup$
I disagree that $-14 mod 12$ doesn't mean anything. I have seen this been treated as the image of $-14$ under the function $mod 12 : mathbb{Z}to mathbb{Z}$ or even of the canonical function $ mathbb{Z}to mathbb{Z}/12mathbb{Z}$. In a computer science course I took this expression was treated as a number.
$endgroup$
– Gunnar Sveinsson
2 hours ago
$begingroup$
I disagree that $-14 mod 12$ doesn't mean anything. I have seen this been treated as the image of $-14$ under the function $mod 12 : mathbb{Z}to mathbb{Z}$ or even of the canonical function $ mathbb{Z}to mathbb{Z}/12mathbb{Z}$. In a computer science course I took this expression was treated as a number.
$endgroup$
– Gunnar Sveinsson
2 hours ago
$begingroup$
Although if "modular aritmetic" is more well defined than I think, you may be right that it doesnt really mean anything in that "field".
$endgroup$
– Gunnar Sveinsson
2 hours ago
$begingroup$
Although if "modular aritmetic" is more well defined than I think, you may be right that it doesnt really mean anything in that "field".
$endgroup$
– Gunnar Sveinsson
2 hours ago
1
1
$begingroup$
The operation $bmod$ is certainly in wide use in mathematics, computer science, etc. So it is incorrect and misleading to claim the it "doesn't mean anything".
$endgroup$
– Bill Dubuque
2 hours ago
$begingroup$
The operation $bmod$ is certainly in wide use in mathematics, computer science, etc. So it is incorrect and misleading to claim the it "doesn't mean anything".
$endgroup$
– Bill Dubuque
2 hours ago
$begingroup$
@BillDubuque I tried to make it clear that I'm talking in the context of modular arithmetic.
$endgroup$
– Arthur
1 hour ago
$begingroup$
@BillDubuque I tried to make it clear that I'm talking in the context of modular arithmetic.
$endgroup$
– Arthur
1 hour ago
$begingroup$
@Arthur And so am I.
$endgroup$
– Bill Dubuque
1 hour ago
$begingroup$
@Arthur And so am I.
$endgroup$
– Bill Dubuque
1 hour ago
add a comment |
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Whenever you get a positive number, you remove $12$ until you get a number between $0$ And $11$ to get the modulo.
Example: $ 37bmod{12}equiv 37-12equiv 25equiv 25-12equiv 13equiv 13-12equiv 1pmod{12}$
For a negative number, in the same way just add $12$ until you get something positive.
Example: $ {-}14bmod{12}equiv -14+12equiv -2equiv -2+12equiv 10pmod{12}$
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add a comment |
$begingroup$
Whenever you get a positive number, you remove $12$ until you get a number between $0$ And $11$ to get the modulo.
Example: $ 37bmod{12}equiv 37-12equiv 25equiv 25-12equiv 13equiv 13-12equiv 1pmod{12}$
For a negative number, in the same way just add $12$ until you get something positive.
Example: $ {-}14bmod{12}equiv -14+12equiv -2equiv -2+12equiv 10pmod{12}$
$endgroup$
add a comment |
$begingroup$
Whenever you get a positive number, you remove $12$ until you get a number between $0$ And $11$ to get the modulo.
Example: $ 37bmod{12}equiv 37-12equiv 25equiv 25-12equiv 13equiv 13-12equiv 1pmod{12}$
For a negative number, in the same way just add $12$ until you get something positive.
Example: $ {-}14bmod{12}equiv -14+12equiv -2equiv -2+12equiv 10pmod{12}$
$endgroup$
Whenever you get a positive number, you remove $12$ until you get a number between $0$ And $11$ to get the modulo.
Example: $ 37bmod{12}equiv 37-12equiv 25equiv 25-12equiv 13equiv 13-12equiv 1pmod{12}$
For a negative number, in the same way just add $12$ until you get something positive.
Example: $ {-}14bmod{12}equiv -14+12equiv -2equiv -2+12equiv 10pmod{12}$
edited 2 hours ago
Bill Dubuque
210k29192640
210k29192640
answered 2 hours ago
zwimzwim
11.9k730
11.9k730
add a comment |
add a comment |
lєαf is a new contributor. Be nice, and check out our Code of Conduct.
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I think it's the latter, but that wouldn't make much sense here. I was playing around with the google calculator when I came up with this equation.
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– lєαf
2 hours ago
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@GunnarSveinsson : I would downvote your comment if I could. There is one and only one sane definition of $a mod n$ (where $n>0$). It is the unique value in $[0,n)$ which can be obtained by adding an integral multiple of $n$ to $a$.
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– MPW
2 hours ago
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@MPW It is true that the first definition / notation is wrong, but it is not true that there is only one definition of operational mod, e.g. it might denote the canonical residue in a system of least magnitude reps, e.g. $, -1,0,1pmod{3}. $ Its definition is relative to the complete system of reps employed.
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– Bill Dubuque
2 hours ago
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@MPW: Taking the latter definition gives you a function that isn't additive (i.e., $text{mod}(a+b, n) not= text{mod}(a, n) + text{mod}(b, n)$ in general, isn't multiplicative, may have strange behavior with negative arguments, and doesn't easily generalize outside the integers. It's convenient in some settings (e.g., programming) to recast $text{mod}$ a function rather than an equivalence relation by taking a single representative of the equivalence class under it, but it's often the far less sane choice.
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– anomaly
1 hour ago
1
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@anomaly : I think of ‘mod’ as giving the representative in the base coset
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– MPW
53 mins ago