What number which best completes the sequence20 5 30 6 42 7?

In the sequence 20 5 30 6 42 7, the rule is divide by 4 then multiply by 6, divide by 5 then multiply by 7, divide by 6 then multiply by 8 since each time the number by which you multiply or divide by increases by 1. Since the last multiplication was by 7, we know the next will be by 8. Therefore, the answer you get for the next number in the sequence is 56 (7x8=56).