Question

the rule for this number sequence is (n+3) x 2
where n is the previous number in the sequence.

6   18  42 ?

type the missing number
please

Answer 1

6 + 12 = 18
18 + 24 = 42
Double the difference between every 2 numbers (12 x 2 = 24 x 2 = 8)
42 + 48 = 90
90 is the missing number
Happy to Help!