A positive integer k is called a "lucky" number if the units digit of k^4 is 6. How many lucky numbers smaller than 1000 are there?
The lucky numbers are the numbers that end with 6. So there are 100 of them that are less than 1000.
There are 400 such numbers beginning with: 2, 4, 6, 8, 12..........and ending with: 992, 994, 996 and 998.
+407 
