101 LearnersLast updated on July 28th, 2025
Subtraction of Binary Numbers Rules
The mathematical operation of finding the difference between two binary numbers is known as the subtraction of binary numbers. It is essential for performing arithmetic operations in digital electronics and computer systems and follows specific rules similar to decimal subtraction.
What is Subtraction of Binary Numbers?
Subtracting binary numbers involves borrowing, similar to decimal subtraction, but with only two digits: 0 and 1.
Binary subtraction requires understanding the rules for each possible pair of binary digits.
The basic components of binary subtraction are:
Binary Digits: The binary system uses only two digits, 0 and 1.
Borrowing: When subtracting 1 from 0, borrowing from the next higher bit is necessary.
Binary Place Values: Each position in a binary number represents a power of 2.
How to Subtract Binary Numbers?
When subtracting binary numbers, follow these rules:
0 - 0 = 0: No borrowing is needed.
1 - 0 = 1: No borrowing is needed.
1 - 1 = 0: No borrowing is needed.
0 - 1 = 1: Borrow 1 from the next higher bit.
Borrowing: When a 1 is borrowed, it is equivalent to adding 2 to the current digit (since binary is base 2).
Methods to Subtract Binary Numbers
The following are the methods for subtracting binary numbers:
Method 1: Borrowing Method
Step 1: Align the binary numbers, ensuring the digits line up correctly.
Step 2: Starting from the rightmost bit, subtract each corresponding bit.
Step 3: Borrow from the next higher digit when subtracting 1 from 0.
Example: Subtract 1010 from 1101.
Step 1: 1101 -1010
Step 2: Start from the right, subtract 0 - 0 = 0.
Step 3: Move left, subtract 1 - 1 = 0.
Step 4: Continue, 0 - 0 = 0.
Step 5: Finally, 1 - 1 = 0.
Answer: 0011
Method 2: Complement Method
This method involves using binary complements and addition to perform subtraction.
Step 1: Find the two's complement of the subtrahend (the number being subtracted).
Step 2: Add the two's complement to the minuend (the number from which to subtract).
Step 3: If there is an overflow, ignore it.
Example: Subtract 1010 from 1101 using complements.
Step 1: Two's complement of 1010 is 0110.
Step 2: Add 1101 + 0110. Step 3: Result is 0011.
Properties of Subtraction of Binary Numbers
In binary arithmetic, subtraction has specific properties:
- Subtraction is not commutative: Changing the order changes the result, i.e., A - B ≠ B - A.
- Subtraction is not associative: Regrouping changes the result, i.e., (A − B) − C ≠ A − (B − C).
- Subtraction is the addition of the opposite: Subtracting a binary number is equivalent to adding its two's complement.
- Subtracting zero leaves the number unchanged: A - 0 = A.
Tips and Tricks for Subtracting Binary Numbers
Tips and tricks can help simplify the subtraction of binary numbers:
Tip 1: Always double-check the borrowing process to ensure accuracy.
Tip 2: Use the complement method for efficient subtraction, especially in complex calculations.
Tip 3: Practice with different examples to become familiar with borrowing and complements.
Forgetting to Borrow
Students often forget to borrow when subtracting 1 from 0. Always check for borrowing needs before simplifying.
Mistake 1
Incorrect Complements
Ensure the correct calculation of the two's complement, as errors can lead to wrong results.
Mistake 2
Misalignment of Bits
When aligning binary numbers, ensure that all bits are properly aligned vertically in the same columns.
Mistake 3
Ignoring Overflow
In complement methods, ignore any overflow beyond the significant bits.
Mistake 4
Missing Borrowing Steps
Ensure all necessary borrowing steps are completed when performing manual subtraction.
Mistake 5
Examples of Subtraction of Binary Numbers
Subtract 1010 from 1101
11
Problem 1
Using the borrowing method: 1101 -1010 = 0011
Subtract 1101 from 10111
Explanation
10010
Problem 2
Using the borrowing method: 10111 - 1101 = 10010
Subtract 1001 from 1110
Explanation
11
Problem 3
Using the borrowing method: 1110 -1001 = 0011
Subtract 101 from 1000
Explanation
11
Problem 4
Using the borrowing method: 1000 - 0101 = 0011
Subtract 111 from 1001
Explanation
1010
Yes, pad the shorter number with leading zeros to match the lengths before subtracting.
1.Is subtraction commutative in binary arithmetic?
2.What are binary complements?
3.What is the first step in subtracting binary numbers using complements?
4.What methods are used for the subtraction of binary numbers?
5.How can children in Philippines use numbers in everyday life to understand Subtraction of Binary Numbers Rules?
6.What are some fun ways kids in Philippines can practice Subtraction of Binary Numbers Rules with numbers?
7.What role do numbers and Subtraction of Binary Numbers Rules play in helping children in Philippines develop problem-solving skills?
8.How can families in Philippines create number-rich environments to improve Subtraction of Binary Numbers Rules skills?
Common Mistakes and How to Avoid Them in Subtraction of Binary Numbers
Subtraction in binary can be tricky, leading to common mistakes. Awareness of these errors can help avoid them.
Hiralee Lalitkumar Makwana
About the Author
Hiralee Lalitkumar Makwana has almost two years of teaching experience. She is a number ninja as she loves numbers. Her interest in numbers can be seen in the way she cracks math puzzles and hidden patterns.
Fun Fact
: She loves to read number jokes and games.
