Home > College Algebra > Number Complement Subtraction > 2's Complement Subtraction example

7's Complement Subtraction example ( Enter your problem )
  1. Example 402 - 314
  2. Example 342 - 614
  3. Example 465 - 371
  4. Example 1256 - 2702
  5. Example 31421 - 7253

5. Example 31421 - 7253





5. Find Subtraction of 31421 and 7253 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 = 31421, B = 07253.
Find A - B = ? using 7's complement
First find 7's complement of B = 07253

Note : 7's complement of a number is obtained by subtracting all bits from 77777

Step-1: 7's complement of 07253 is obtained by subtracting each digit from 77777
77777
-07253

70524



Step-2: Now Add this 70524 to 31421

1
31421
+70524

122145


Step by step solution of 31421 + 70524 = 122145

Write the numbers, so that each digit lines up vertically

31421
+70524


Step-1 :
`=1_8+4_8`
`=1_10+4_10`
`=5_10`
`=5_8`
Write the 5 in the sum place

31421
+70524

5

Step-2 :
`=2_8+2_8`
`=2_10+2_10`
`=4_10`
`=4_8`
Write the 4 in the sum place

31421
+70524

45

Step-3 :
`=4_8+5_8`
`=4_10+5_10`
`=9_10`
`=8xx1+1`
`=11_8`
Write the 1 in the sum place and carry the 1 to the next carry place

1
31421
+70524

145

Step-4 :
`=1+1_8+0_8`
`=1+1_10+0_10`
`=2_10`
`=2_8`
Write the 2 in the sum place

1
31421
+70524

2145

Step-5 :
`=3_8+7_8`
`=3_10+7_10`
`=10_10`
`=8xx1+2`
`=12_8`
Write the 12 in the sum place

1
31421
+70524

122145



The left most bit (1) of the result (122145) is called carry and add it to the rest part of the result (22145)
22145
+ 1

22146



So answer is 22146




This material is intended as a summary. Use your textbook for detail explanation.
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