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Home > Maths I > Measure and Shape > Time calculations

Maths I

Time calculations

Calculating time intervals (continued)

Counting On

Remember the original question:

Daniel starts school at 8.25am and finishes at 3.15pm. How long does his school day last?

This is how to work it our using the 'counting on' method.

Start at 8.25am and work out the number of minutes until 9 am.

8.25am - 9am = 35 mins

Next work out how many hours there are between 9am and 3pm.

9am - 12noon = 3 hrs

12noon - 3pm = 3 hrs

Next calculate the number of minutes between 3pm and 3.15pm.

3pm - 3.15pm = 15mins

Finally add up the separate time intervals.

3hrs + 3hrs + 15mins + 35mins = 6hrs50 mins.

Example

Amy used the internet from 1008 until 1457. How long was she on it for?

Add up the time intervals

1hr + 2hrs + 57mins + 52mins = 3hrs109mins

Of course 109mins is a silly answer.

60mins is one hour.

109 - 60 = 49

109mins = 1hr + 49mins.

3hrs + 1hr + 49mins

The total time Amy spent on the internet was 4hrs49mins

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