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

Solution:

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.

Here A = 670, B = 831.
Find A - B = ? using 9's complement
First find 9's complement of B = 831


Step-1: 9's complement of 831 is obtained by subtracting each digit from 999

	9	9	9
-	8	3	1
	1	6	8

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Step-2: Now Add this 168 to 670

	1
	6	7	0
+	1	6	8
	8	3	8

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Step by step solution of 670 + 168 = 838

Write the numbers, so that each digit lines up vertically

	6	7	0
+	1	6	8

Step-1 :
`=0+8`
`=8`
Write the 8 in the sum place

	6	7	0
+	1	6	8
			8

Step-2 :
`=7+6`
`=13`
Write the 3 in the sum place and carry the 1 to the next carry place

	1
	6	7	0
+	1	6	8
		3	8

Step-3 :
`=1+6+1`
`=8`
Write the 8 in the sum place

	1
	6	7	0
+	1	6	8
	8	3	8

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


Step-1: 9's complement of 838 is obtained by subtracting each digit from 999

	9	9	9
-	8	3	8
	1	6	1

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So answer is -161

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