1
Adding and taking away zero
Learner’s Book 1: Unit 13, pp. 194–195
GoalAdd 0 to a number and subtract 0 or the whole number, and say what happens.
New words
zero (0) · none, nothingadd zero · add nothing, so the number stays the samesubtract zero · take away nothing, so the number stays the same
Explanation
Zero means none. When we add zero to a number we add nothing, so the number stays the same: 7 + 0 = 7. If we start at 0 and add a number, we land on that number: 0 + 4 = 4. When we subtract zero we take away nothing, so 7 − 0 = 7. When we take away all of a number, nothing is left: 7 − 7 = 0. On a number line, a jump of 0 stays in the same place.
Worked examples
Ravi has 6 counters and gets none more. 6 + 0 = 6.
Start at 0 and jump 8. You land on 8. So 0 + 8 = 8.
11 − 0 = 11, because nothing is taken away. But 11 − 11 = 0, because all 11 are taken away and none are left.
Class activity
Zero stories: tell a partner a short story where nothing is added (a bag with 5 sweets, and you add none) and a story where everything is taken away. Say the number sentences. What is the same in all of them?
Practice
1
What is 5 + 0?
5
2
What is 0 + 9?
9
3
What is 16 − 0?
16
4
What is 4 − 4? Start at 4 and jump back 4.
0