 # Convert Octal to Binary

In order to convert octal to binary number, we have to follow a few steps. Octal numbers have base 8 and binary numbers have base 10. We cannot directly convert an octal number into a binary number, but by converting the octal into a decimal number, which has base 10. Then we will proceed to convert the decimal number into its equivalent binary number. Before we learn the conversion method, let us learn about both the number systems.

Octal Numbers: Octal numbers are the numbers which have base 8. It is represented as N8. It uses the digits 0,1, 2, 3, 4, 5, 6 and 7 to represent the numbers in this number system. For example:

• 1128
• 10088
• 7898, etc.

Binary Numbers: Binary numbers have base 2 and are represented by two digits, i.e. 0 and 1. They are the combination of binary digits, 0s and 1s. These numbers have wide application in the computer system to store data. For example:

• 00112
• 1111012
• 1010102

## How to Convert Octal To Binary?

Conversion of octal to binary number is a two-step process. First, we need to convert the given octal number into its equivalent decimal number and then convert the decimal into binary. Let us learn the complete steps here.

### Octal to Decimal Conversion

• Count the number of digits present in the given number. Let the number of digits be ‘n’.
• Now multiply each digit of the number with 8n-1, when the digit is in the nth position from the right end of the number. If the number has a decimal part, multiply each digit in the decimal part by `8-m` when the digit is in the mth position from the decimal point.
• Add all the terms after multiplication.
• The obtained value is the equivalent decimal number.

### Decimal to Binary Conversion

• Take the above-produced decimal number and divide it by 2.
• Note down the remainder.
• Continue the above two steps for the quotient till the quotient is zero.
• Write the remainder in the reverse order.
• The received number is the equivalent binary number for the given octal number.

### Octal To Binary Conversion Examples

Q.1: Convert 418 to a binary number.

Solution: Given number is 418

418 = (4 * 81) + (1 * 80)

= 4 * 8 + 1 * 1

= 32+1

= 33(Decimal number)

Now convert this decimal number into its equivalent binary number. Let us draw a table to show the conversion of decimal to binary as given below.

 Decimal Number divided by 2 Quotient Remainder 33 divided by 2 16 1 16 divided by 2 8 0 8 divided by 2 4 0 4 divided by 2 2 0 2 divided by 2 1 0 1 divided by 2 0 1

Therefore, the equivalent binary number is 1000012.

Hence, 418 = 1000012

Q.2: Convert 108 to a binary number.

Solution: Given number is 108

108 = (1 * 81) + (0 * 80)

= 1 * 8 + 0 * 1

= 8 + 0

= 8 (Decimal number)

Now convert this decimal number into its equivalent binary number. Let us draw a table to show the conversion of decimal to binary as given below.

 Decimal Number divided by 2 Quotient Remainder 10 divided by 2 5 0 5 divided by 2 2 1 2 divided by 2 1 0 1 divided by 2 0 1

Therefore, the equivalent binary number is 10102.

Hence, 108 = 10102

## Convert Octal to Binary Using Table

We can also use the octal number table to convert a number with base 8 to a number with base 2. Using this table we can also convert a binary number to an octal number. First, let us write the table.

 Octal Number Equivalent Binary Number 0 000 1 001 2 010 3 011 4 100 5 101 6 110 7 111

Example: Convert 128 into a binary number.

Solution: Given, 128 is the octal number.

Now with the help of the table, we can write;

128 = (001 010)2

Since zeros on the left, most of digit 1 does not have any significance. Thus,

128 = (1010)2

### Practice Questions

1. Convert 1228 into binary number.
2. Convert the octal number 2008 into its equivalent binary number.
3. Convert (98)8 to a binary number.