Addition fact families (a+b=c, c-b=a)

A fact family describes a relationship between 3 numbers.  The relationship could be through addition or subtraction.  

This video shows how we can use fact families to help us answer questions. 

Worked Examples

Question 1

We are interested in the fact family of $$1,$$8 and $$9.

	$$+		$$=
$$8	$$+	$$1	$$=	$$9

1. What is $$1+8?

2. What is $$9−8?

3. What is $$9−1?

Reveal SolutionWatch video

Question 2

We are interested in the fact family of $$2, $$4 and $$6:

	$$−		$$=
$$6	$$−	$$4	$$=	$$2

1. What is $$2+4?

2. What is $$6−2?

3. What is $$4+2?

Reveal SolutionWatch video

Question 3

We are interested in the fact family of $$2,$$4 and $$6:

	$$+		$$=	?
$$2	$$+	$$4	$$=	?

1. What is $$2+4?

2. What is $$4+2?

3. What is $$6−4?

4. When looking at the answer to $$6−2, is the answer going to be less than $$10?

   Yes

   A

   No

   B

5. What is $$6−2?

Reveal SolutionWatch video