The correct approach is to show that you can break down the problem. 2^32 = 2^10 * 2^10 * 2^10 * 2^2. 2^10 = 2^8 * 2*2 = 256 * 4 ~(roughly) 1000 So: 2^32 ~ 1000 * 1000 * 1000 * 4 = 4,000,000,000