2. Find Subtraction of 342 and 614 using 7's complement

Solution:

7's complement subtraction steps :

1. At first, find 7'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 7's complement of the sum is the final result and it is negative.

Here A = 342, B = 614.
Find A - B = ? using 7's complement
First find 7's complement of B = 614


Step-1: 7's complement of 614 is obtained by subtracting each digit from 777

	7	7	7
-	6	1	4
	1	6	3

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Step-2: Now Add this 163 to 342

	1
	3	4	2
+	1	6	3
	5	2	5

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Step by step solution of 342 + 163 = 525

Write the numbers, so that each digit lines up vertically

	3	4	2
+	1	6	3

Step-1 :
`=2_8+3_8`
`=2_10+3_10`
`=5_10`
`=5_8`
Write the 5 in the sum place

	3	4	2
+	1	6	3
			5

Step-2 :
`=4_8+6_8`
`=4_10+6_10`
`=10_10`
`=8xx1+2`
`=12_8`
Write the 2 in the sum place and carry the 1 to the next carry place

	1
	3	4	2
+	1	6	3
		2	5

Step-3 :
`=1+3_8+1_8`
`=1+3_10+1_10`
`=5_10`
`=5_8`
Write the 5 in the sum place

	1
	3	4	2
+	1	6	3
	5	2	5

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Here there is no carry, answer is - (7's complement of the sum obtained 525)


Step-1: 7's complement of 525 is obtained by subtracting each digit from 777

	7	7	7
-	5	2	5
	2	5	2

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So answer is -252

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