N is a base ten positive integer formed by writing the digit 7 precisely 2010 times, that is N = 77....77 (2010 times).

Determine the digital root of [N/199].

Note: [x] denotes the greatest integer ≤ x.

*** For an extra challenge, solve this problem without using a computer program.

There are a lot of 7's.

Posted by Math Man on 2011-01-05 15:28:21