Units of time
Hours, minutes and seconds are the units to measure time. An hour is the largest unit to measure time from the hour hand of clock. Second is the smallest unit measured from the second hand. Minute is used to measure time which the minute hand tells. Each of these three units of time are interchangeable. The table below summarizes the how they are related to each other.
| Unit of time | Equals to |
|---|---|
| 1 hour | 60 minutes |
| 1 minute | 60 seconds |
Using conversion factors from the above table, the values of hours, minutes and seconds can be changed into one another.
Conversions of time
Each unit of time hours, minutes and seconds can be changed into one and another with the following methods:
Hours into minutes
To convert hours into minutes, the value of hours is multiplied by 60 because 1 hour = 60 minutes.
1 hour = 60 minutes
Let's understand how hour can be changed into minutes with the solved examples as below:
Convert 8 hours into minutes
As we know 1 hour = 60 minutes
Multiply 8 by 60
∴ 8 hours = 8 × 60 = 480 minutes
Minutes into hours
Minutes can be converted into hours by dividing the given minutes by 60.
Convert 240 minutes into hours
Because 60 minutes = 1 hour
Divide 240 by 60
∴ 240 minutes = 240 ÷ 60 = 4 hours
Minutes into seconds
Minutes are converted into seconds by multiplying them by 60.
1 minute = 60 seconds
Convert 15 minutes into seconds
Because 1 minute = 60 seconds
∴ To convert 15 minutes into seconds, just multiply 15 by 60.
i.e. 15 × 60 = 900 seconds
∴ 15 minutes = 900 seconds
Seconds into minutes
Seconds are converted into minutes by dividing seconds by 60.
Convert 540 seconds into minutes
∴ Divide 540 seconds by 60.
i.e. 540 ÷ 60 = 9 minutes
Hours into seconds
To convert hours into seconds, first hours are changed into minutes by multiplying hours with 60. After getting the result in minutes, again the result is multiplied by 60 to get seconds. Hence hours are multiplied by 60 twice i.e. 60 × 60 = 3600 to change them into seconds .
1 hour = 3600 seconds
Convert 12 hours into seconds
Because 1 hour = 3600 seconds
∴ Multiply 12 hours with 3600 to get the seconds.
i.e. 12 × 3600 = 43200 seconds
Seconds into hours
Seconds are converted into hours by simply dividing hours by 3600.
Convert 72000 seconds into hours
Divide 72000 seconds by 3600 to get the hours.
i.e. 72000 ÷ 3600 = 20 hours
Operations on times
Two times can be added same like how two numbers are added up. It is as simple as we do the addition operation in arithmetic.
Add times
Minutes and hours are added separately by starting addition first on minutes and lastly on hours. Let's learn it with an example.
When sum of minutes ≤ 60
After adding minutes, if the sum of minutes comes out to be 60 or less than 60. Then the answer will have the calculated minutes. Hours will also be added up as normal addition.
Add 2 hours 40 minutes and 3 hours 10 minutes
When sum of minutes > 60
There are cases when sum of minutes becomes larger than 60 minutes. In such cases, the minutes in addition to 60 are calculated. These extra minutes are kept in the answer and an extra hour is carried over to the sum of given hours.
Add 4 hours 25 minutes and 6 hours 45 minutes
Here, the sum of minutes is 65, which is more than 60.
So, minutes additional to 60 are calculated.
Total minutes = 65 minutes - 60 minutes = 5 minutes
Sum of hours = 10
An extra will be added in 10. So, carry over 1 hour to hours columns.
Total hours = 10 + 1 = 11 hours
So, the sum of 4 hours 25 minutes and 6 hours 45 minutes becomes 11 hours 5 minuets.
Subtract times
Two times can also be subtracted same like the subtraction operation in arithmetic.
Subtract 6 hours 25 minutes from 10 hour 40 minutes
Subtract 5 hours 20 minutes from 7 hour 10 minutes
Since, 10 minutes in 7 hour 10 minutes is less than 20 minutes in 5 hour 20 minutes.
So, borrow 1 hour from 7 hours in hours columns and it into 10 minutes in minutes columns
i.e. reduce 7 hours by 1 hour or 7 - 1 = 6.
7 hours in 7 hour 10 minutes becomes 6 hours
Also, 1 hour = 60 minutes
So, we can convert 1 hour into 60 minutes while borrowing and add it into 10 minutes in minutes column.
10 minutes in 7 hour 10 minutes will become 10 + 60 = 70 minutes
7 hour 10 minutes can be written as 6 hour 70 minutes after borrowing 1 hour.
The answer of subtraction 5 hours 20 minutes from 7 hour 10 minutes is 1 hour 50 minutes.
Subtract 3 hours 35 minutes from 11 hour 12 minutes
Since, 12 minutes in 11 hour 12 minutes is less than 35 minutes in 3 hour 35 minutes.
So, 1 hour is borrowed from 11 hours and added to 12 minutes
i.e. 11 hours becomes 11 - 1 = 10 hours
While borrowing convert 1 hour into 60 minutes and added to 12 minutes
12 minutes becomes 12 + 60 = 72 minutes
11 hour 12 minutes can be written as 10 hour 72 minutes after borrowing 1 hour.
The answer of subtraction of 3 hours 35 minutes from 11 hour 12 minutes is 7 hour 37 minutes.
