What is the decimal number 24 written in binary?

The decimal number 24 is written as 11000 in binary.

Binary is a base-2 numeral system, so each position represents a power of two rather than a power of ten. Reading 11000 from right to left gives place values 1, 2, 4, 8, and 16. The two rightmost positions are zero, while the 16 and 8 positions are switched on. Therefore, 11000₂ equals 16 + 8, or 24₁₀.

Another way to find the result is repeated division by two. Dividing 24 by two produces remainders 0, 0, 0, 1, and 1 when continued to zero. Reading those remainders upward gives 11000. This method works for any positive whole number.

A common mistake is choosing 11100, which represents 28, or 10100, which represents 20. The decimal number 24 should not be confused with the binary numeral 24: binary digits can contain only 0 and 1, so “24” itself is not a valid binary numeral.