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January 29, 2015

January 29, 2015

Posted by **charlie** on Sunday, May 2, 2010 at 5:42pm.

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.

Charlie

- math -
**MathMate**, Sunday, May 2, 2010 at 5:49pmAn integer that leaves a remainder of 1 when divided by 7 can be represented by

7m+1, or 7n+1, where m, n are integers.

The product is thus:

(7m+1)(7n+1)

Expand the product and complete the proof.

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