15×256
15×256 is the product of the integers 15 and 256. In base-10 notation it equals 3840. It can be computed as 10×256 plus 5×256, giving 2560 + 1280 = 3840. Because 256 is 2^8, the product is 15×2^8, i.e., 3840, which corresponds to the binary value obtained by shifting 15 left by eight bits. In binary this is 111100000000, and in hexadecimal it is 0x0F00.
The prime factorization is 2^8 × 3 × 5, since 256 = 2^8 and 15 = 3×5. The result
Summary: 15×256 equals 3840, with representations in binary (111100000000) and hex (0x0F00), and prime factors 2^8