What is the digit in the tens place when 7^2008 is expressed in decimal notation?
7^2008 mod10^10==8326964801 - these are the last 10 digits.
7^2 = 49
7^3 = 343
7^4 = 2401
7^5 = 16807
7^6 = 117649
7^7 = 823543
7^8 = 5764801
.
7^(2n).....when n is odd, the tens digit = 4
7^(2n).....when n is even, the tens digit = 0
7^(2008) = 7^(2 * 1004) → the tens digit = 0
