# Addition and Subtraction of Octal Numbers

Addition and subtraction of octal numbers are explained using different examples.

Addition of octal numbers is carried out by the same principle as that of decimal or binary numbers.

An addition table for octal numbers is given below:

 + 0 1 2 3 4 5 6 7 0 0 1 2 3 4 5 6 7 1 1 2 3 4 5 6 7 10 2 2 3 4 5 6 7 10 11 3 3 4 5 6 7 10 11 12 4 4 5 6 7 10 11 12 13 5 5 6 7 10 11 12 13 14 6 6 7 10 11 12 13 14 15 7 7 10 11 12 13 14 15 16

With the help of this table addition of octal numbers is best illustrated by the following examples:

Evaluate:

(i) (162)8 + (537) 8

Solution:

1 1          <---- carry

1 6 2

5 3 7
7 2 1

Therefore, sum = 7218

(ii) (136) 8 + (636) 8

Solution:

1           <---- carry

1 3 6

6 3 6
7 7 4

Therefore, sum = 7748

(iii) (25.27) 8 + (13.2) 8

Solution:

1                   <---- carry

2 5 . 2 7

1 3 . 2
4 0 . 4 7

Therefore, sum = (40.47) 8

(iv) (67.5) 8 + (45.6) 8

Solution:

1 1                  <---- carry

6 7 . 5

4 5 . 6
1 3 5 . 3

Therefore, sum = (135.3) 8

Subtraction of octal numbers:

Similarly, subtraction of octal numbers can be performed by following the rules of subtraction of decimal numbers.

Thus, for performing addition and subtraction of octal numbers we can follow the rules of addition and subtraction of decimal numbers

• Why Binary Numbers are Used
• Binary to Decimal Conversion
• Conversion of Numbers
• Hexa-decimal Number System
• Conversion of Binary Numbers to Octal or Hexa-decimal Numbers
• Octal and Hexa-Decimal Numbers
• Signed-magnitude Representation
• Arithmetic Operations of Binary Numbers