1. Find Subtraction of 402 and 314 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 = 402, B = 314.
Find A - B = ? using 7's complement
First find 7's complement of B = 314


Step-1: 7's complement of 314 is obtained by subtracting each digit from 777

	7	7	7
-	3	1	4
	4	6	3

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Step-2: Now Add this 463 to 402

	4	0	2
+	4	6	3
1	0	6	5

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Step by step solution of 402 + 463 = 1065

Write the numbers, so that each digit lines up vertically

	4	0	2
+	4	6	3

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

	4	0	2
+	4	6	3
			5

Step-2 :
`=0_8+6_8`
`=0_10+6_10`
`=6_10`
`=6_8`
Write the 6 in the sum place

	4	0	2
+	4	6	3
		6	5

Step-3 :
`=4_8+4_8`
`=4_10+4_10`
`=8_10`
`=8xx1+0`
`=10_8`
Write the 10 in the sum place

	4	0	2
+	4	6	3
1	0	6	5

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The left most bit (1) of the result (1065) is called carry and add it to the rest part of the result (065)

	0	6	5
+			1
	0	6	6

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So answer is 066