What number completes this sequence 20 5 30 6 42 7?

Answer 1

Not sure about "completes" but one possible answer for the next number in the infinite sequence is 32. Why?

It is generated by the polynomial:

t(n) = (-n4 + 14n3 - 65n2 + 136n - 180)/12 for n = 1 , 2, 3, etc.

Answer 2

The squence stated begins with 20. The number is then divided by 4. The next number is the divider + 1 multiplied by the quotient.

The next numbers would be 8x7 and 7+1, ie. 56 and 8

Answer 3

11 is the next number, it goes up one more than the last time each one so +2 +3, +4.. so on, so on.

Answer 4

Because 5x6=30, 6x7=42, 7x8=56,8x9=72....

Answer 5

56