Two's complement of 100
The 8-bit two's complement of 100 is 10011100, the bit pattern that represents -100 (minus 100). Written as a signed 8-bit number, 100 itself is 01100100.
Invert and add 1
Here is the two's complement of 100 at 8 bits, step by step (invert the bits of 100 and add 1):
- Write 100 in 8-bit binary:
01100100. - Invert every bit (the one's complement):
10011011. - Add 1:
10011100.
100 at 4, 8, and 16 bits
| Width | 100 as a signed number | Two's complement of 100 |
|---|---|---|
| 4-bit | — | — |
| 8-bit | 01100100 | 10011100 |
| 16-bit | 0000000001100100 | 1111111110011100 |
A dash means 100 (or its negation) is outside that width's signed range: 4-bit two's complement holds -8 to 7, 8-bit holds -128 to 127, and 16-bit holds -32768 to 32767.
Reading 100 as a binary pattern
The digits of 100 are all 0s and 1s, so "two's complement of 100" often means the 3-bit binary number 100 itself, not the decimal 100. As a signed 3-bit value that pattern is -4. Its two's complement is 100: invert 100 to 011 and add 1.
100 is the most negative 3-bit value (-4), and negating the most negative value overflows back to itself. That is why the two's complement of 100 is again 100.
Convert any number
Two's complement is how computers store signed integers, so one adder can both add and subtract. Read the full two's complement lesson, or convert any value at 8, 16, or 32 bits with the two's complement calculator.
Want to see two's complement do real work? Open the lab and wire a subtractor from an adder and inverters, or follow the free course from a transistor up to an 8-bit CPU.
Open the two's complement calculator →Frequently asked
What is the two's complement of 100?
The 8-bit two's complement of 100 is 10011100, the bit pattern for -100. You get it by writing 100 in binary (01100100), inverting every bit (10011011), then adding 1.
How do you write 100 in two's complement?
100 in 8-bit two's complement is 01100100. Positive numbers are identical to plain binary, so no inverting is needed. At 16 bits it is 0000000001100100.
What is the two's complement of 100 (as binary)?
Reading 100 as a 3-bit binary pattern, its two's complement is 100: invert 100 to 011 and add 1. (100 is the most negative 3-bit value, so negating it overflows back to itself.)