Decide which number makes the addition number sentence true. You can think of an addition fact you know, or you can subtract to find the answer.
The addition fact is:
1+9=10
Did you remember this addition fact? If not, you can find the answer by subtracting.
Subtract:
10–9=1
The missing number is 1.

Decide which number makes the addition number sentence true. You can think of an addition fact you know, or you can subtract to find the answer.
The addition fact is:
1+9=10
Did you remember this addition fact? If not, you can find the answer by subtracting.
Subtract:
10–1=9
The missing number is 9.

Decide which number makes the addition number sentence true. You can think of an addition fact you know, or you can subtract to find the answer.
The addition fact is:
6+4=10
Did you remember this addition fact? If not, you can find the answer by subtracting.
Subtract:
10–6=4
The missing number is 4.