71.0k views
2 votes
Describe how to use a tens fact to find the difference for 15-8

2 Answers

3 votes
you can round 15 to 20 and 8 and to 10
User SonOfTheEARTh
by
8.4k points
4 votes

How to use mental strategies to subtract within 20 using the "break down to 10" strategy? With practice, this strategy can help students gain fluency when subtracting within 20. By now children should be very comfortable with the sum-equals-ten addition and subtraction facts, such as 4+6=10 and 10-7=3.

Write 15-8=? on the board. Explain that:

1. 15=10+5;

2. 8=5+3;

3. 15-8=10+5-5-3=10-3=7.

Answer: 15-8=7.

User Linas Valiukas
by
7.8k points

No related questions found