Strings with 4 factors to get to 840

2 x 420

3 x 280

4 x 210

5 x 168

6 x 140

7 x 120

8 x 105

10 x 84

12 x 70

14 x 60

15 x 56

20 x 24

21 x 40

24 x 35

28 x 30

2 x 2 x 210

2 x 3 x 140

2 x 5 x 84

2 x 7 x 60

3 x 5 x 56

3 x 7 x 40

5 x 7 x 24

2 x 2 x 2 x 105

2 x 2 x 3 x 70

2 x 2 x 5 x 42

2 x 2 x 7 x 30

2 x 3 x 5 x 28

2 x 3 x 7 x 20

3 x 5 x 7 x 8

2 x 2 x 2 x 3 x 35

2 x 2 x 2 x 5 x 21

2 x 2 x 2 x 7 x 15

22.

1. 0.3 •4 is the same as 4 groups of 0.32. 7•0.8 is the same as 7 groups of 0.83. it increases by 0.5 every time, so 0.5x4 it increases by 0.9 every time, so 0.9x5. 0.9•12=10.86. 0.47•5=2.35i can finish the next ones in a separate post