build 10, 15 and 20
5 + ? = 10
what is ?
5
What is the double of 4?
8
40 + 15 = ?
What is ?
55
70 - 10 = ?
What is ?
60
If 2 + 5 = 7, than 20 + 50 = ?
What is ?
70
? + 4 = 10
What is ?
6
What is the double of 6?
12
60 + 35 = ?
What is ?
95
80 - 25 = ?
What is ?
55
If 4 + 6 = 10, than 40 + 60 = ?
What is ?
100
? + 7 = 15
What is ?
8
What is the double of 12?
24
10 + 55 = ?
What is ?
94 - 21 = ?
What is ?
73
What known fact would help you to solve
30 + 50 = 80
3 + 5 = 8
12 + ? = 15
What is ?
3
What is the double of 9?
18
72 + 11 = ?
What is ?
83
68 - 32 = ?
What is ?
36
If 1 + 8 = 9, than ? + 80 = 90
What is ?
10
? + 13 = 20
What is ?
7
What is the double of 15?
30
33 + 46 = ?
What is ?
79
44 - 34 = ?
What is ?
10
If 1 + 2 = 3, than ? + 20 = ?
What is ? and ?
10 and 30