How many three-digit numbers can be expressed as an integral power of 2?

Three-digit numbers range from 100 to 999. Powers of 2: 2^6 = 64 (two-digit), 2^7 = 128, 2^8 = 256, 2^9 = 512, 2^10 = 1024 (four-digit). So the three-digit integral powers of 2 are 128, 256, and 512 — exactly 3 numbers.