4. Find Subtraction of 2870 and 1943 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 = 2870, B = 1943.
Find A - B = ? using 9's complement
First find 9's complement of B = 1943


Step-1: 9's complement of 1943 is obtained by subtracting each digit from 9999

	9	9	9	9
-	1	9	4	3
	8	0	5	6

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Step-2: Now Add this 8056 to 2870

		1
	2	8	7	0
+	8	0	5	6
1	0	9	2	6

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Step by step solution of 2870 + 8056 = 10926

Write the numbers, so that each digit lines up vertically

	2	8	7	0
+	8	0	5	6

Step-1 :
`=0+6`
`=6`
Write the 6 in the sum place

	2	8	7	0
+	8	0	5	6
				6

Step-2 :
`=7+5`
`=12`
Write the 2 in the sum place and carry the 1 to the next carry place

		1
	2	8	7	0
+	8	0	5	6
			2	6

Step-3 :
`=1+8+0`
`=9`
Write the 9 in the sum place

		1
	2	8	7	0
+	8	0	5	6
		9	2	6

Step-4 :
`=2+8`
`=10`
Write the 10 in the sum place

		1
	2	8	7	0
+	8	0	5	6
1	0	9	2	6

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The left most bit (1) of the result (10926) is called carry and add it to the rest part of the result (0926)

	0	9	2	6
+				1
	0	9	2	7

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So answer is 0927

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