Multiply 2, 3, and 4
Multiply 5 and 6
Multiply 7 and 8
find the unknown number
repeat addition
100

2 x 9 =

18

100

5 x 3 =

15

100

7 x 2 =

14

100

n x 8 = 16

n = 2

100

5 + 5 + 5 + 5=

4 x 5 = 20

200

3 x 6 =

18

200

6 x 4 =

24

200

8 x 3 = 

24

200

5 x b = 25

b = 5

200

7 + 7 + 7 =

3 x 7 = 21

300

7 x 4 =

28

300

5 x 7 =

35

300

8 x 5 =

40

300

30 / n = 3

n = 10

300

9 + 9 + 9 =

3 x 9 = 27

400

3 x 9 =

27

400

6 x 8 =

48

400

7 x 6 =

42

400

k / 4 = 6

k = 24

400

10 + 10 + 10 + 10 + 10 =

5 x 10 = 50

500

4 x 9 =

36

500

6 x 9 =

54

500

7 x 8 =

56

500

9 x c = 63

c = 7

500

6 + 6 + 6 + 6 + 6 + 6 + 6 + 6 + 6 =

9 x 6 = 54

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