Last digits of 2^n have a cycle of four: 2, 4, 8, 6.
Last digits of 3^n have a cycle of four: 3, 9, 7, 1.
Last digits of 7^n have a cycle of four: 7, 9, 3, 1.
The total therefore has a cycle of four: 2, 2, 8, 8.
This means, depending on n mod 4 being 0 through 3, the values are 8, 2, 2 and 8 respectively.

Posted by Charlie
on 20110117 18:14:02 