Binary addition questions with solutions are given here to practise the addition and subtraction of binary numbers. Binary numbers are base – 2; every number in this system is expressed as 0’s and 1’s.

Other number systems are:

Binary numbers are of great importance as they are used in digital electronics. The symbol 0 represents the OFF position, and 1 represents the ON position. Each symbol represents a bit used to operate any digital system like computers, calculators etc.

Like decimal numbers, we can perform the addition and subtraction of binary numbers. Following are rules for the addition of binary numbers.

  • 0 + 0 = 0
  • 0 + 1 = 1
  • 1 + 0 = 1
  • 1 + 1 = 0; carry 1
  • 1 + 1 + 1 = 1; carry 1

We shall use these rules to perform the addition of binary numbers.

Learn more about Binary addition.

Binary Addition Questions with Solutions

Solve the following questions to practise binary addition.

Question 1:

Add the following binary numbers:

(i) 11010 + 11100

(ii) 101011 + 110101

Solution:

(i)

1

1

0

1

0

+

1

1

1

0

0

1

1

0

1

1

0

∴ 11010 + 11100 = 110110

(ii)

1

0

1

0

1

1

+

1

1

0

1

0

1

1

1

0

0

0

0

0

∴ 101011 + 110101 = 1100000

Question 2:

Add the following binary numbers:

(i) 11011 + 10001

(ii) 10101 + 110001

Solution:

(i)

1

1

0

1

1

+

1

0

0

0

1

1

0

1

1

0

0

∴ 11011 + 10001 = 101100

(ii)

1

0

1

0

1

+

1

1

0

0

0

1

1

0

0

0

1

1

0

∴ 10101 + 110001 = 1000110

Question 3:

Add the following binary numbers:

(i) 11110000 + 1000011001

(ii) 10101000 + 010001001

Solution:

(i)

1

1

1

1

0

0

0

0

+

1

0

0

0

0

1

1

0

0

1

1

1

0

0

0

0

1

0

0

1

∴ 11110000 + 1000011001 = 1100001001.

(ii)

1

0

1

0

1

0

0

0

+

0

1

0

0

0

1

0

0

1

1

0

0

1

1

0

0

0

1

∴ 10101000 + 010001001 = 100110001.

Question 4:

Add the following binary numbers:

(i) 0011010 + 111001

(ii) 1010111 + 1001111

Solution:

(i)

0

0

1

1

0

1

0

+

1

1

1

0

0

1

1

0

1

0

0

1

1

∴ 0011010 + 111001 = 1010011

(ii)

1

0

1

0

1

1

1

+

1

0

0

1

1

1

1

1

0

1

0

0

1

1

0

∴ 1010111 + 1001111 = 10100110.

Question 5:

Add the following binary numbers:

(i) 100001111 + 111001101

(ii) 101011111 + 110011010

Solution:

(i)

1

0

0

0

0

1

1

1

1

+

1

1

1

0

0

1

1

0

1

1

0

1

1

0

1

1

1

0

0

∴ 100001111 + 111001101 = 1011011100.

(ii)

1

0

1

0

1

1

1

1

1

+

1

1

0

0

1

1

0

1

0

1

0

1

1

1

1

1

0

0

1

∴ 101011111 + 110011010 = 1011111001.

Also Check:

Question 6:

Add the following binary numbers: 11110 and 101101

Solution:

1

1

1

1

0

+

1

0

1

1

0

1

1

0

0

1

0

1

1

∴ 11110 + 101101 = 1001011.

Subtraction of Binary Numbers

Subtraction in digital systems is done by adding a negative signed binary number. Computers used signed numbers to represent negative numbers.

Usually, we subtract numbers by finding the two’s complement. If A and B represent two binary numbers, then,

A – B = A + 2’s complement of B

The subtraction of binary numbers works as given below:

  • 0 − 0 = 0
  • 0 − 1 = 1, borrow 1
  • 1 − 0 = 1
  • 1 − 1 = 0

Learn more about Binary subtraction.

Question 7:

Subtract 11010 from 111101.

Solution:

Since the minuend is of 6-bits, we make the subtrahend also of 6-bits

6-bits subtrahend = 011010

1’s complement of 011010 = 100101

2’s complement of 011010 = 1’s complement of 011010 + 1

= 100101 + 1

= 100110

Now, 111101 – (011010) = 111101 + 100110

1

1

1

1

0

1

+

1

0

0

1

1

0

(1)

1

0

0

0

1

1

We see that one bit (1) is overflowing; hence, we ignore that bit

∴ 111101 – (011010) = 100011

Question 8:

Subtract 1001 from 1101.

Solution:

Using the rules of binary subtraction:

1

1

0

1

–

1

0

0

1

0

1

0

0

∴ 1101 – 1001 = 100

Question 9:

Subtract 111001 from 1111001.

Solution:

Using the rules of binary subtraction:

1

1

1

1

0

0

1

–

1

1

1

0

0

1

1

0

0

0

0

0

0

∴ 1111001 – 111001 = 1000000.

Question 10:

Subtract 100100 from 11100010 using 2’s complement.

Solution:

Since the minuend is 8-bit, we also make the subtrahend to 8-bit

8-bit subtrahend = 00100100

1’s complement of 00100100 = 11011011

2’s complement of 00100100 = 1’s complement of 00100100 + 1

= 11011011 + 1 = 11011100

Now, 11100010 – 100100 = 11100010 + 11011100

1

1

1

0

0

0

1

0

+

1

1

0

1

1

1

0

0

(1)

1

0

1

1

1

1

1

0

We see that one bit (1) is overflowing; hence, we ignore that bit

∴ 11100010 – 100100 = 10111110.

You can also check your answers with a Binary operations calculator.

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Practice Questions on Binary Addition

1. Add the following binary numbers:

(i) 110101 + 11010011

(ii) 100110 + 01011101

(iii) 1111 + 11000

(iv) 10011 + 11001

(v) 1100111 + 111001

2. Subtract the following binary numbers using subtraction rules:

(i) 11011 from 11110

(ii) 10101 from 11000

(iii) 111000 from 1101101

3. Subtract the following using the 2’s complement:

(i) 1100001 from 111100001

(ii) 1100 from 11111

(iii) 10001 from 101111

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