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