10101001 binary to decimal

Binary to Decimal Converter

What is binary 10101001 in decimal?

Answer

Binary number 10101001 in decimal is

169

Read as an unsigned binary number — each place is worth a power of 2, 2⁰ on the right.

If this is an 8-bit signed number, the first bit is the sign: −41 in sign-magnitude, −86 in ones’ complement, −87 in two’s complement.

Digit × place value, then add

128 + 32 + 8 + 1 = 169

Binary number 10101001 in decimal is 169

Binary 10101001 in hexadecimal is A9 (0xA9): group the bits by four from the right — 1010 = A, 1001 = 9.

As an 8-bit signed number: −41 in sign-magnitude, −86 in ones’ complement, −87 in two’s complement. Unsigned it is 169.