what is the next number in the sequence 3, -6, 12, 4, 20, ?

Question

 what is the next number in the sequence 3, -6, 12, 4, 20, ?

Answer 1

THe operation changes from subtraction to addition beginning with 9, doubling the difference every other time.

Then the difference decreased by 1 and the pattern starts over.

 

3 - 9 = -6.                             (2 x 9 = 18)

 

-6 + 18 = 12.                      Now the difference decreases to 8.

 

12 - 8 = 4 .                            2 x 8 = 16

 

4 + 16 = 20.                      Now the difference decreases to 7

 

20 - 7 = 13.                         2 x 7 = 14

 

13 + 14 = 27