Register to reply

9's complement

by snoggerT
Tags: complement
Share this thread:
Feb15-09, 05:40 PM
P: 186
Find the 4-digit complement of a) 0232 b) 9644

3. The attempt at a solution

I'm not really sure what is being asked here. When asked what form the numbers were given in and whether the problem was talking about 9's complement, his response was "the answer is 9's complement". So I don't really know what to do since they appear to be in 9's complement form already. Does anyone think they can help?
Phys.Org News Partner Science news on
Experts defend operational earthquake forecasting, counter critiques
EU urged to convert TV frequencies to mobile broadband
Sierra Nevada freshwater runoff could drop 26 percent by 2100
Feb15-09, 08:16 PM
P: 366
One of the uses of 9's complement notation is to convert a decimal into its negative form so that an addition can be performed instead of subtraction, thus obviating the necessity of borrowing, etc.

The nine's complement can be obtained by subtracting from nine of each and every digit of the original number.

For example, the nine's complement of 1357 would be 8642, since 9-1=8, 9-3=6, 9-5=4, 9-7=2.

To do a subtraction, we simply add the first number to the nine's complement of the second number, PLUS 1, then ignore the 'Carry'.

For example, to do 524-256
we calculate 524+743+1=1268, drop the 1 (carry) to give 268.

See for example:'s_complement
Feb15-09, 08:24 PM
P: 186
thanks. I just wanted to make sure on that.

Register to reply

Related Discussions
Complement of XOR, what is it? Electrical Engineering 13
2's complement Electrical Engineering 2
2's complement Engineering, Comp Sci, & Technology Homework 2
Sign magnitude/1's Complement/2's Complement HELP! Engineering, Comp Sci, & Technology Homework 0
2's complement in VB Programming & Computer Science 2