3 × 50 = 3 × 5 × 10         

           = 15 × 10

           = 150

2 × 80 = 2 × 8 × 10

           = 16 × 10

           = 160

9 × 70 = 9 × 7 × 10

           = 63 × 10

           = 630

3 × 200 = 3 × 2 × 100

             = 6 × 100

             = 600

4 × 300 = 4 × 3 × 100

             = 12 × 100

             = 1 200

5 × 300 = 5 × 3 × 100

             = 15 × 100

             = 1 500

2 × 4 000 = 2 × 4 × 1 000

                = 8 × 1 000

                = 8 000

3 × 7 000 = 3 × 7 × 1 000

                = 21 × 1 000

                = 21 000

6 × 2 000 = 6 × 2 × 1 000

                = 12 × 1 000

                = 12 000