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Maths · Measure

Calculate a duration

Find elapsed time between two clock or timetable entries.

Free to use and free to share. There is no sign-up, no score, and nothing a child does here is recorded or sent anywhere.

Practise it now

The football match starts 1h 20m after 08:05. Wind the clock forward to find out when.

It covers most of this skill rather than all of it.

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A worked example

One question of the kind this skill is tested with, worked all the way through: the reasoning, and what the wrong answers are there to catch.

Counting minutes between two clock times

How many minutes are there between the Start time and the Finish time for Football?

Sessions at the half-term holiday club.

SessionStart timeFinish time
Football13:5414:14
Baking15:4516:32
Swimming09:4610:30
  1. 60 minutes
  2. 40 minutes
  3. 80 minutes
  4. 20 minutes

Answer: 20 minutes

How you get there

The clock passes 14:00 on the way, so counting on from 13:54 to 14:00 and then on to 14:14 is what keeps the hour honest: 13:54 to 14:14 is 20 minutes, so Football takes 20 minutes. Taking one clock reading away from the other as if they were ordinary numbers gives a different answer, because an hour is 60 minutes and not 100.

Why the other answers tempt

An hour is 60 minutes, so the digits on a clock cannot be subtracted the way ordinary numbers are.

If they are stuck, say this

Count on from the earlier time to the next whole hour, then on to the later time, and add the two counts together.

Now do it live in Clock & Coins

What this exercise is doing

Clock & Coins

The football match starts 1h 20m after 08:05. Wind the clock forward to find out when.

Winding forward 1h 20m from 08:05 lands on 09:25 - the hour hand moves too, one twelfth as fast as the minute hand, which is why it sits between the numbers. Then 30p takes at least 3 coins from this tray: there is no 10p in it, so you have to build the amount from what is actually there.

  1. Step 1. Wind the clock. Wind the minute hand forward 1h 20m from 08:05.
  2. Step 2. Count the coins. A programme costs 30p. Drag coins into the purse to pay it exactly.

What to say if they get stuck

  1. Grab the long minute hand and wind it forwards. Watch the little hour hand creep round with it.
  2. One whole lap of the minute hand is one hour. You need 1h 20m.
  3. For the coins, start with the biggest coin that fits inside 30p and keep going.

Open Clock & Coins on its own page to share it

How calculate a duration differs from the skills beside it

The same exercise practises several skills, and telling them apart is often the difficulty rather than the exercise itself. On this page the skill is: find elapsed time between two clock or timetable entries, and it stops where one continuous interval.

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Questions parents ask about calculate a duration

Answered from what the skill map records about this skill, not from a template. Every answer here is on the page, and the same questions are the page's FAQ structured data.

Find elapsed time between two clock or timetable entries. It is one of 55 named maths skills in the 11+, in the measure strand, and this page carries 1 interactive exercise that practises it.

Knowing which maths topic to practise is most of the work

A free diagnostic covers arithmetic, fractions, geometry, measure and data handling, and comes back with the topics to spend the next few weeks on.