A string of 2001 digits begins with a "6". Any number formed by two consecutive digits is divisible by either 17 or 23.

What is the last digit in this sequence?

What if the sequence had 2002 digits?

Just to clarify vivek's comment: with 2001 digits, the last must always be 6, but with 2002, the last digit can be 8 or 9.

And a nit: 00 is also divisible by 17 and 23, but is obviously useless.

Posted by Rick on 2003-02-07 05:26:23