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Finding the difference
Learner’s Book 1: Unit 13, pp. 193–194
GoalFind how far apart two numbers are, and subtract 0 and all of a number.
New words
difference · how far apart two numbers arezero (0) · none, nothingsubtract 0 · take away nothing
Explanation
The difference between two numbers tells us how far apart they are. Put both numbers on a number line and count the jumps between them. The difference between 5 and 12 is 7, because we jump 7 from 5 to 12. We can write 12 − 5 = 7. When we subtract 0, we do not move, so 9 − 0 = 9. When we take away all of a number, nothing is left, so 9 − 9 = 0.
Worked examples
The difference between 7 and 10 is 3, because we jump 3 from 7 to 10.
The difference between 9 and 16 is 7, because we jump 7 from 9 to 16.
Sam has 17 cards and Mia has 12 cards. The difference is 5, so Sam has 5 more cards than Mia. 17 − 12 = 5.
Class activity
Difference game: each player rolls a dice twice to make two numbers, or picks two number cards from 0 to 20. Put both on a number line. Say the difference. The player with the bigger difference wins a point.
Practice
1
What is the difference between 4 and 11?
7
2
What is the difference between 8 and 15?
7
3
What is 12 − 0?
12
4
Aisha has 14 pebbles and Ben has 9 pebbles. How many more pebbles does Aisha have?
5