You know the partners of 10 and counting back. Now let’s make all the facts within 10 quick.
Key idea
Facts that use the same three numbers make a fact family: $5 + 3 = 8$, $3 + 5 = 8$, $8 - 5 = 3$, $8 - 3 = 5$.
Why it works
Adding puts the two parts together. Subtracting takes one part away from the whole. Same parts, same whole, so if you know one fact, you know four.
Worked example: Use a fact you know
Use $6 + 4 = 10$ to find $10 - 4$.
- 6 and 4 make 10.
- Take the 4 away from 10, and the 6 is left.
- $10 - 4 = 6$
Answer: 6
For grown-ups: A few minutes of quick facts every day works better than one long session. Mix in “turn-around” facts and their subtraction partners.