15

1 × 15

3 × 5

2 × 15 = 30

3 × 15 = 45

4 × 15 = 60

152 = 225

10 × 15 = 150

http://mathsfaculty.net

20

1 × 20

2 × 10

4 × 5

2 × 20 = 40

3 × 20 = 60

4 × 20 = 80

202 = 400

10 × 20 = 200

5 × 20 = 100

http://mathsfaculty.net

25

1 × 25

5 × 5

2 × 25 = 50

3 × 25 = 75

4 × 25 = 100

252 = 625

25 ÷ 2 = 121

2

=25 5

http://mathsfaculty.net

30

1 × 302 × 15

3 × 10

2 × 30 = 60

3 × 30 = 90

4 × 30 = 120

302 = 900

30 ÷ 2 = 15

5 × 6

http://mathsfaculty.net