Describe two's complement.

Two's complement is improvement on one's complement.
To get a negative number in One's complement, one has to invert all numbers (turn 1 to 0, and 0 to 1), for two's complement is the same but add 1 (e.g. in 4 bit, 0001).
For example to get a negative -5 in 4 bit:Positive 4: 01002Invert positive 4: 10112, this is negative -4 in one's complement.Add 0001 to inverted positive 4: 1100
A simple way to read the two's complements binary number: usually, from left most to right we see each bit as [8, 4, 2, 1], but for two's complement we (humans) can read it as [-8, 4, 2, 1], so 1100 would be -8 +4, which is -4.
Though, two's complement is more common for two reasons.In one's complement there are two representations for 0 (in 4 bit it would be 0000 and 1111).When adding a positive and a negative number you also need to add 1 (e.g. in 4 bit, 0001) after the operation.

LP
Answered by Lukas P. Computing tutor

1871 Views

See similar Computing A Level tutors

Related Computing A Level answers

All answers ▸

What is the point of an Operating System?


One member of a chess club sends a text file saved in Unicode. What meant by the term "Unicode" and why might this be necessary?


Convert the hexadecimal '3E', which represents a 2's compliment binary number, in decimal.


Represent the denary number 5.625 as an unsigned binary fixed point number with three bits before and five bits after the binary point.


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning