What is the smallest integer greater than 0 that can be written entirely with zeros and ones and is evenly divisible by 225?
The factors of 225 are 3, 3, 5, 5. To get two fives in the number it must end in 00. To be divisable by 3 twice the sum of the digits must be 9. So the smallest number using only ones and zeros is 11111111100/225=49382716.