Question

What is the next number in the sequence 3, 12, 24, 33, 66

Answer 1

The answer is 75.
The pattern goes like this: +9, x2, +9, x2, etc. 
3+9=12x2+24+9=33x2=66+9+75.
Hope this helped! :)

Answer 2

75.
Explanation: from 3 to 12, you add 9, and then double the 12 to get to 24, and then add 9 again to get to 33, and double it to get 66, so the pattern is to add 9 and then double.