Re: prime numbers and African artifact

Martin Bright (martin@melon.wdg.uk.ibm.com)
12 Jul 1995 16:00:49 GMT

Peter Seebach (seebs@solutions.solon.com) wrote:
|> > What's the easy way to show that 254365465431652436514232 is not
|> >prime again?

|> Simple!

|> 2 + 5 + 4 + 3 + 6 + 5 + 4 + 6 + 5 + 4 + 3 + 1 +
|> 6 + 5 + 2 + 4 + 3 + 6 + 5 + 1 + 4 + 2 + 3 + 2 = 91

|> 9 + 1 = 10.

|> 1 + 0 = 1.

|> 1 is not a multiple of three, so the whole number is not a multiple of
|> three, so it must be prime!

Also the first two digits aren't divisible by 4, so the whole number isn't
divisible by 4. This proves again that it is prime.

Martin

--



Martin Bright, Pre-University Employee    |  mbright@vnet.ibm.com

Warwick Development Group, IBM UK         |  9BRIGHM at NHBVM9