CBSE Class 11 | Number System 3

Binary to Decimal conversion

How to convert binary to decimal

For binary number with n digits:

dn-1 … d3 d2 d1 d0

The decimal number is equal to the sum of binary digits (dn) times their power of 2 (2n):

decimal = d0×20 + d1×21 + d2×22 + …

Example:1

Find the decimal value of 11001:

Convert (11001)2 to (n)10

binary number: 1 1 0 0 1
power of 2: 24 23 22 21 20

=> 1*24 + 1*23 + 0*22 + 0*21 + 1*20
=> 16 + 8 + 0 + 0 + 1
=> 25

So we have

(11001)2 = (25)10

Example:2

Find the decimal value of 1101:

Convert (1101)2 to (n)10

Binary Number 1 1 0 1
Power of 2 23 22 21 20

=> 1*23 + 1*22 + 0*21 + 1*20
=> 8 + 4 + 0 + 1
=> 13

So we have

(1101)2 = (13)10

Example:3

Find the decimal value of 10011:

Convert (10011)2 to (n)10

Binary Number 1 0 0 1 1
Power of 2 24 23 22 21 20

=> 1*24 + 0*23 + 0*22 + 1*21 + 1*20
=> 16 + 0 + 0 + 2 + 1
=> 19

So we have

(10011)2 = (19)10