2
Take away from 20
Joyful Mathematics: Chapter 6
GoalTake away from numbers up to 20 and say how many are left.
New words
take away · make the group smallerleft · what staystwenty · two tens, 20
Explanation
We can take away from bigger numbers too. Look at 18 stars. Cross out 5 stars. Count what is left: 13. So 18 − 5 = 13. Count the ones that are not crossed. Say the last number you counted.
Worked examples
15 − 3 = 12. 3 kites are crossed out.
17 − 8 = 9. 8 lemons are crossed out.
20 − 10 = 10. There are 20 sweets for Eid. Friends eat 10 of them, so 10 are left.
Class activity
Cross and count. Draw 16 circles in two rows on paper. Cross out 7 with a pencil. Count the circles that are left and say: 16 − 7 = 9. Then try 13 − 5 and 18 − 6.
Practice
1
How many frogs are left?
9.
2
How many cups are left?
11.
3
What is 19 − 6?
13.
4
Sana has 17 beads. She uses 7 beads. How many beads are left?
10.
5
What is 20 − 5?
15.