103 LearnersLast updated on July 28th, 2025
Subtraction of Hours and Minutes
The mathematical operation of finding the difference between two time periods is known as the subtraction of hours and minutes. This process helps calculate durations, solve time-related problems, and manage schedules effectively.
What is Subtraction of Hours and Minutes?
Subtracting hours and minutes involves taking one time period from another. This requires careful attention to the units of hours and minutes, ensuring that minutes are subtracted correctly, even when borrowing is necessary.
The components involved in this operation are:
Hours: These are whole number units of time.
Minutes: These are fractional units of an hour, with 60 minutes making up one hour.
Borrowing: When the minutes in the minuend are less than those in the subtrahend, you borrow one hour (60 minutes) from the hours.
How to do Subtraction of Hours and Minutes?
When subtracting hours and minutes, follow these rules:
Borrow when necessary: If the minutes in the minuend are less than those in the subtrahend, borrow an hour from the hours to add 60 minutes to the minuend's minutes.
Subtract minutes: Once borrowing is done, subtract the minutes of the subtrahend from those of the minuend.
Subtract hours: Subtract the hours of the subtrahend from those of the minuend.
Methods to do Subtraction of Hours and Minutes
The following are methods to subtract hours and minutes:
Method 1: Standard Method
To apply the standard method for subtracting hours and minutes, use these steps.
Step 1: Write the time periods with hours and minutes clearly labeled.
Step 2: If needed, borrow one hour from the hours column to the minutes column.
Step 3: Subtract the minutes and then the hours.
Example: Subtract 2 hours 45 minutes from 5 hours 30 minutes.
Step 1: Write the time periods: 5 hours 30 minutes - 2 hours 45 minutes
Step 2: Borrow 1 hour: 4 hours 90 minutes
Step 3: Subtract: 2 hours 45 minutes
Answer: 2 hours 45 minutes
Method 2: Conversion Method
Convert the entire time into minutes, perform the subtraction, and then convert back to hours and minutes.
Example: Subtract 1 hour 50 minutes from 3 hours 10 minutes.
Solution: Convert to minutes: 3 hours 10 minutes = 190 minutes
1 hour 50 minutes = 110 minutes
Subtract: 190 minutes - 110 minutes = 80 minutes
Convert back: 1 hour 20 minutes
Therefore, the difference is 1 hour 20 minutes.
Properties of Subtraction of Hours and Minutes
Subtraction of time has characteristic properties, as listed below:
- Not commutative: Changing the order of time periods changes the result, i.e., A - B ≠ B - A.
- Not associative: Rearranging time periods affects the outcome. (A - B) - C ≠ A - (B - C)
- Borrowing: Often necessary when the minutes of the minuend are less than those of the subtrahend.
- Subtracting zero: Subtracting zero minutes or hours leaves the original time unchanged. A - 0 = A
Tips and Tricks for Subtraction of Hours and Minutes
Here are some useful tips and tricks for subtracting hours and minutes efficiently:
Tip 1: Always check if borrowing is needed before subtracting minutes.
Tip 2: Use the conversion method for complex calculations, as it simplifies the subtraction process.
Tip 3: Practice mental math with smaller time periods to improve speed and accuracy.
Forgetting to borrow
Students often forget to borrow 1 hour when the minuend's minutes are less than the subtrahend's. Always ensure borrowing is done when necessary.
Mistake 1
Incorrect conversion
Ensure correct conversion between hours and minutes when using the conversion method. Double-check calculations to avoid errors.
Mistake 2
Misalignment in columns
When using the column method, ensure hours and minutes are clearly aligned vertically to avoid miscalculations.
Mistake 3
Leaving time without simplification
Always simplify the final time result, converting excess minutes into hours if necessary.
Mistake 4
Ignoring missing minutes
For missing minutes, consider using a placeholder of zero. If a particular time period lacks minutes, treat it as having 0 minutes to maintain proper alignment.
Mistake 5
Examples of Subtraction of Hours and Minutes
Subtract 1 hour 50 minutes from 4 hours 30 minutes
2 hours 40 minutes
Problem 1
Using the standard method: 4 hours 30 minutes - 1 hour 50 minutes Borrow 1 hour: 3 hours 90 minutes Subtract: 2 hours 40 minutes
Subtract 2 hours 25 minutes from 6 hours
Explanation
3 hours 35 minutes
Problem 2
Using the conversion method: 6 hours = 360 minutes 2 hours 25 minutes = 145 minutes Subtract: 360 minutes - 145 minutes = 215 minutes Convert back: 3 hours 35 minutes
Subtract 3 hours 15 minutes from 7 hours 5 minutes
Explanation
3 hours 50 minutes
Problem 3
7 hours 5 minutes - 3 hours 15 minutes Borrow 1 hour: 6 hours 65 minutes Subtract: 3 hours 50 minutes
Subtract 45 minutes from 2 hours
Explanation
1 hour 15 minutes
Problem 4
Convert to minutes: 2 hours = 120 minutes Subtract: 120 minutes - 45 minutes = 75 minutes Convert back: 1 hour 15 minutes
Subtract 1 hour 40 minutes from 5 hours 20 minutes
Explanation
3 hours 40 minutes
Yes, if the minuend's minutes are greater than the subtrahend's, borrowing is unnecessary.
1.Is subtraction commutative with time?
2.What is borrowing in time subtraction?
3.What is the first step in subtracting hours and minutes?
4.What methods are used for time subtraction?
5.How can children in Australia use numbers in everyday life to understand Subtraction of Hours and Minutes?
6.What are some fun ways kids in Australia can practice Subtraction of Hours and Minutes with numbers?
7.What role do numbers and Subtraction of Hours and Minutes play in helping children in Australia develop problem-solving skills?
8.How can families in Australia create number-rich environments to improve Subtraction of Hours and Minutes skills?
Common Mistakes and How to Avoid Them in Subtraction of Hours and Minutes
Subtraction of time can be tricky, leading to common mistakes. Being aware 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.
