Thinking Aloud

October 1, 2005

A conjecture for breakfast, anyone?

Filed under: Mathematics - uliang @ 12:31 am

Here’s something to go with your coffee and eggs in the morning.

Do you know the answer to this?

1) If you have 3 odd prime numbers, is it always true that there is at least one of the three that divides the product of the other two leaving remainder one. ( Let p,q,r be three distinct odd primes. Is it true that at least one of these cases happens? qr = 1 mod p, pq = 1 mod r or pr = 1 mod q.)

I think it’s true, but can’t prove it.

2 Comments »

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  1. er…if we consider 5,7,11

    then
    5.7 = 2 mod 11
    5.11 = 6 mod 7
    7.11 = 2 mod 5

    Is that a counter-example? Or did I miss something?

    Comment by marcus — October 1, 2005 @ 1:33 pm

  2. hehe…that’s right. It is a counter example, seems I didn’t really bother looking hard enough…*blush*

    Comment by uliang — October 1, 2005 @ 2:56 pm

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