42 in binary
The decimal number 42 written in binary is 101010. In hexadecimal it is 2A, and in octal 52.
| Base | Value |
|---|---|
| Decimal (base 10) | 42 |
| Binary (base 2) | 101010 |
| Hexadecimal (base 16) | 2A |
| Octal (base 8) | 52 |
How 42 converts to binary
Binary is base 2, so each place is worth twice the one to its right: 1, 2, 4, 8, 16, and so on. Adding up the place values that have a 1 gives back the decimal number:
32 + 8 + 2 = 42
That is why 42 in decimal is 101010 in binary: it is exactly the set of powers of two that add up to 42. To get the hexadecimal form, group the bits into fours from the right and write each group as one hex digit, which gives 2A.
Convert any number
Type any value and watch all three bases update live in the binary converter, or read the theory behind it in the lessons on binary numbers and hexadecimal.
Want to build the circuit that does this? Open the lab and wire up an adder, or follow the free course from a single transistor up to an 8-bit CPU.
Open the binary converter →Frequently asked
What is 42 in binary?
42 in binary is 101010. That is the sum of the powers of two 32 + 8 + 2, which add up to 42.
What is 42 in hexadecimal?
42 in hexadecimal is 2A. You get it by grouping the binary digits 101010 into fours from the right and writing each group as one hex digit.
How many bits is 42?
42 needs 6 bits in binary (101010). It fits in a single 8-bit byte.