Counting Back to Subtract

Subtraction Facts Strategies

Ways to attack subtraction facts!

Counting Back

Counting back is helpful for when you are subtracting 1 or 2 from a number.

Example: 7 - 2

All you need to do is count back from 7 two numbers...so 7-6-5.

7-2 = 5

Counting Up

When numbers are really close together you can count up to see the difference between the numbers. Let's look at the subtraction fact

12 - 9. These numbers are pretty close on a number line so I won't have to count too much if I start at 9 and count up to 12... 9, 10, 11, 12

I only counted up 3 numbers so the difference is 12 - 9 = 3

Doubles

Most of us know our doubles facts...

2 + 2 =4, 3 + 3 = 6, 4 + 4 =8, 5 + 5 =10

6 + 6 =12 and so on! We can use this knowledge to help us when we have a doubles subtraction fact...

Example

10- 5 =(we can think 5 + 5 =10) so

10 - 5 = 5

Or 12 - 6 = 6 because 6 + 6 = 12

Backwards Addition

Some addition math facts you just know! You can use that knowledge to solve subtraction facts. Subtraction is the opposite of addition. The have a special relationship. So if you know that 7 + 6 = 13 then you can use that to solve 13 -7 You can think 7 + ___ = 13 and you will have your answer of 8!