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The hexadecimal numeral system is a place-value numeral system based on the powers of 16. It is an efficient shorthand for computer programmers to use instead of the binary numeral system.

For example, 11001001 is C9:

 ${\displaystyle 2^{7}}$ ${\displaystyle 2^{6}}$ ${\displaystyle 2^{5}}$ ${\displaystyle 2^{4}}$ ${\displaystyle 2^{3}}$ ${\displaystyle 2^{2}}$ ${\displaystyle 2^{1}}$ ${\displaystyle 2^{0}}$ 128s 64s 32s 16s 8s 4s 2s 1s 1 1 0 0 1 0 0 1 C 9 ${\displaystyle 16^{1}}$ ${\displaystyle 16^{0}}$