Page 767 - AP Computer Science A, 7th edition
P. 767
19. (D) Think of the integer as having 31 slots for storage. If there were just one slot, the maximum binary number would be 1 = 21
− 1. If there were just two slots, the maximum binary number would be 11 = 22 − 1 = 3. If there were just eight slots, the maximum binary number would be 11111111 = 28 − 1. So for 31 slots, the maximum value is 231 – 1.
