Missing ones and tens

Sheet 9

I am learning to  find missing ones and tens.

1.
15 +  21  = 36
5 +  1  =6
10 +  20   = 30


2.
21 + 15 =36  
1+ 5 = 6
20 +10=30
5 +10= 15

3.
21 +  1 3 = 34
1 +  3  =4
20 +  10   = 30

4.
20 + 2 0 =46
0 +   0  =6
20 + 20  = 40
5.