18 : 3 =
24 : 4 =
12 : 2 =
9 : 1 =
81 : 9 =
36 : 4 =
18 : 9 =
8 + 24 =
17 - 15 =
54 : 9 =
: 8 = 4
72 - 40 =
8 : 4 =
20 - 18 =
72 : 8 =
1 +1 =
