# Partition of Integers with mod

1. Dec 17, 2012

### nicnicman

1. The problem statement, all variables and given/known data
Are the following subsets partitions of the set of integers?

The set of integers divisible by 4, the set of integers equivalent to 1 mod 4, 2 mod 4, and 3 mod 4.

2. Relevant equations

3. The attempt at a solution
Yes, it is a partition of the set of integers. Consider 4/4 = 1, 5/4 = 1 R 1, 6/4 = 1 R 2, 7/4 = 1 R 3.

However, how would you create a negative number like -5?

2. Dec 17, 2012

### Dick

I'm not too clear on what your argument is supposed to mean. What's R? But -5=3 mod 4 since (-5)=(-2)*4+3. Hmm, I think I see. R means 'remainder', yes?

Last edited: Dec 17, 2012
3. Dec 17, 2012

### nicnicman

Sorry, I forgot to mention this is far from a formal proof. R just means remainder.

4. Dec 17, 2012

### Dick

Yeah, it is far from formal. But I see what you are doing. Are you supposed to give something formal or just answer yes or no?

5. Dec 17, 2012

### nicnicman

Just answer yes or no. And, you answered my question. I'm pretty sure the answer is yes. Thanks.