What is the next number in the pattern? 3,-6,12,4,20, ?

Question

Next number in the pattern 3, -6, 12, 4, 20, ?

Answer 1

Let's look at the pattern of changes:

-6 - 3 = -9

12 - -6 = 18

4 - 12 = -8

20 - 4 = 16

The changes have a pattern of -9, -8, continuing to -7, -6, and so on, and a pattern of 18, 16, continuing to 14, 12, and so on.

The sequence -9, 18, -8, 16, should continue like this:  -9, 18, -8, 16, -7, 14, -6, 12, and so on.

After the 16 would be -7, so 20-7=13

The next number should be 13.

 

Note:  This isn't the only solution.  There are an infinite number of solutions, but this should be the simplest solution.  It should be the one your teacher/book is looking for.