Question

Using 1's complement method, solve 54(10)
-87
(10)​

Answer 1

1. Method & Examples

Method : 9's complement subtraction steps :

1. At first, find 9's complement of the B(subtrahend).

2. Then add it to the A(minuend).

3. If the final carry over of the sum is 1, then it is dropped and 1 is added to the result.

4. If there is no carry over, then 9's complement of the sum is the final result and it is negative.

1. Find Subtraction of 470 and 231 using 9's complement method

Here A = 470, B = 231.

Find A - B = ? using 9's complement

First find 9's complement of B = 231

Note : 9's complement of a number is obtained by subtracting all bits from 999.

9's complement of 231 is

9 9 9

- 2 3 1

7 6 8

Now Add this 9's complement of B to A

1 1  

4 7 0

+ 7 6 8

1 2 3 8

The left most bit of the result is called carry and add it to the rest part of the result 238.

2 3 8

+   1

2 3 9

So answer is 239

2. Find Subtraction of 670 and 831 using 9's complement method

Here A = 670, B = 831.

Find A - B = ? using 9's complement

First find 9's complement of B = 831

Note : 9's complement of a number is obtained by subtracting all bits from 999.

9's complement of 831 is

9 9 9

- 8 3 1

1 6 8

Now Add this 9's complement of B to A

1  

6 7 0

+ 1 6 8

8 3 8

Here there is no carry, answer is - (9's complement of the sum obtained 838)

Note : 9's complement of a number is obtained by subtracting all bits from 999.

9's complement of 838 is

9 9 9

- 8 3 8

1 6 1

So answer is -161

This answer is an example