Hoofdbewerkingen met natuurlijke getallen

Front

42

Back

4 x 3 = 12
12 + 9 = 21

21 x 2 = 42

Front

4

Back

8 ÷ 2 = 4

6 – 5 = 1
4 ÷ 1 = 4

Front

40

Back

8 + 8 = 16

16 – 6 = 10

4 x 10 = 40

Front

17

Back

6 - 1 = 5

5 x 2 = 10

10 + 7 = 17

Front

31

Back

7 - 2 = 5

6 x 5 = 30

30 + 1 = 31

Front

32

Back

7 + 1 = 8

6 - 2 = 4

8 x 4 = 32