The computer data and the file size is measured in binary code, using the binary number system, which is counted by factors of two, which are 1, 2, 4, 8, 16, etc. The prefixes for the multiples are based on the metric system, and the nearest binary number to 1000 is 2^10 (2 to the power of 10), which is 1024. Hence, the number 1024 is the conversion number.