What is meant by (mod#)?

Question

bibby · Answer

modulus. think of it as the remainder after a division 25 mod 24 = 1

anonymous · Answer

I think it means base right? Like adding in different bases

ex: I've seen 20+13(mod26)=7

doc.brown · Answer

I always think of a clock's hours as being in mod 12.
3 o'clock + 18 hours = 9 o'clock

asnaseer · Answer

Think of mod like this:$$a\text{ }mod\text{ }b$$means take multiples of $b$ away from $a$ until you are left with a number that is less than $b$.

For your example:$$20+13\text{ }mod(26)=33\text{ }mod(26)=7$$since $33=26\times1+7$

misty1212 · Answer

$$a\equiv b(\text{ mod }n)$$ means  $a-b$ divides $n$

asnaseer · Answer

@doulikepiecauseidont - do you understand it now or would you like more explanation?

anonymous · Answer

Yea, I understand, but could you do a little more. I remember seeing this in a numberphile video but I don't think they went that far.

bibby · Answer

continuing with the 12 hour clock idea
13 mod 12 = 1
12 mod 12 = 0
11 mod 12 = 11

asnaseer · Answer

what do you mean by "...but I don't think they went that far"?

anonymous · Answer

in detail

anonymous · Answer

I was asking if you have anymore details about it I should know, just the basics, or if you already said it, thanks

asnaseer · Answer

so from what I have told you so far would you be able to work out 23 mod 17?

anonymous · Answer

6

asnaseer · Answer

correct

asnaseer · Answer

you might find these helpul: http://www.math.rutgers.edu/~erowland/modulararithmetic.html http://betterexplained.com/articles/fun-with-modular-arithmetic/

anonymous · Answer

Ok, thanks, can you do multiplication or anything, kinda like what @misty1212  was saying

asnaseer · Answer

there is a whole theory on modular (or sometimes called clock) arithmetic.

take a look at the sites I mentioned above.

if you still have questions after this then ping me on here and I will try to explain anything you are stuck on.

good luck! :)