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

Hints : (Move mouse over the steps for detail calculation highlight)

Step-1 `=0+8` `=8` `:.` Sum`=8`	Step-2 `=7+6` `=13` `:.` Sum`=3` and carry`=1`
Step-3 `=1+4+7` `=12` `:.` Sum`=2` and carry`=1`

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