What is the rule for the following sequence of numbers: 3, 12, 30, 66, 1) multiply by 4, add 6 2) add 2, multiply by 3 3) multiply by 4 4) add 3, multiply by 2

The sequence is: 3 , 12 , 30 , 66

12-3 = 9
30-12 = 18
66-30 = 36

18/9 = 2
36/18 = 2

Because the difference of 2 of the numbers  divided by the difference of the other 2 numbers is equal to 2, on of the steps is multiplying the previous number by 2,
 But since the previous number multiplied by 2 does not equal the next number, the other step needed is to add 3 first.

 The answer is 4) add 3, multiply by 2