Calculate the difference in different contexts | Exit Quiz | Oak National Academy

When would we be best to use the ‘counting on’ strategy to find the difference?

• When the numbers are close together.

• When the numbers are far apart.

• If we cannot work out the answer.

Answer explanation

We use the ‘counting on’ strategy to find the difference between numbers that are close together, for example 6 and 8 are close together, so we could use a ‘counting on’ strategy.

If a book costs £4 and a toy car costs £12, how would we efficiently calculate the difference in price?

• Subtract £4 from £12

• Count on from £4 to £12

• Add £4 and £12

Answer explanation

To find the difference between £4 and £12, we would subtract £4 from £12, bridging 10 These amounts are far apart, so starting at £4 and ‘counting on’ would not be the most efficient strategy.

A teddy costs £9 and a toy car costs £12, how would we calculate the difference in price?

• Subtract £9 from £12

• Count on from £9 to £12

• Add £9 and £12

Answer explanation

We use the ‘counting on’ strategy when numbers are close together. 9 and 12 are close together, so we could ‘count on’ from £9 to £12

It takes Sofia 4 minutes to walk to school. It takes Jun 12 minutes to walk to school. How much longer does it take Jun to walk to school than Sofia? (a)   minutes.

Answer explanation

12 - 4 = 8, so the difference between 4 and 12 is 8 It takes Jun 8 more minutes to walk to school than Sofia.

Jacob wants to buy a new pencil case that costs £12 and he has saved £9 so far. How much more money does Jacob need to save? £ (a)  

Answer explanation

12 - 9 = 3 The difference between 12 and 9 is 3, so Jacob needs to save £3 more to buy the pencil case.

When playing a game, the difference between Izzy’s score and Lucas’ score is 3, Izzy scored 9 so how many points could Lucas have scored?

(a)  

Answer explanation

3 more than 9 is 12, and 3 less than 9 is 6, so Lucas could have scored 12 or 6 points.