posted by charlie on .
I have this question to work on, and I don't know where to start investigating the answer:
The product of any two (whole) numbers each of which leave a remainder of 1 on dividing by 7, also leaves a remainder of 1 on dividing by 7. Why?
I THINK that I can see a quadratic in there ( (n+1)(2n+1) ); and when I multiply any variation out, there's always a remainder 1.
Can anyone confirm the link; and point me where to go next? Could i use a diagram to explain it? Thanks.