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Multiply the units of 2 and 3
multiply by 4 and 5
Multiply by 6 and 7
repeat addition
find the unknown number
100

3 x 2 =

6

100

4 x 2 =

8

100

6 x 2 =

12

100

2 + 2 + 2 =

3 x 2 = 6

100

n x 7 = 14

n = 2

200

3 x 6 =

18

200

5 x 3 =

15

200

7 x 2 =

14

200

4 + 4+ 4 =

3 x 4 = 12

200

7 x m = 28

m = 4

300

2 x 9 =

18

300

4 x 5 =

20

300

4 x 7 =

28

300

2 + 2 + 2 + 2 + 2 =

5 x 2 = 10

300

5 x k = 35

k = 7

400

3 x 7 =

21

400

5 x 9 =

45

400

6 x 7 =

42

400

6 + 6 + 6 + 6 =

4 x 6= 24

400

24 / 3 = y 

y = 8

500

3 x 9 =

27

500

4 x 8 =

32

500

8 x 7 =

56

500

9 + 9 + 9 + 9 =

4 x 9 = 36

500

48 / 6 = j

j = 8