Depends:
It could be -366 - if you fit a quintic polynomial to the 6 points.
or
It could be 212 - if the sequence is +1, *4, +1, *4 etc
11
11
13
13 if you refer to a number line. If you subract you will get -1-12 = -13
12 and 13
What would be the next number in this series 15 12 13 10 11 8?
20
8
240
13 is one possibility.
The next number is 13... you're adding the previous two numbers together to produce the next in line.
Each ascending number is equal to the square of the next prime number multiplied by (the prime number plus one). In this case, 11 squared x 12 = 1452. Therefore, the next number in the sequence is equal to 13 squared x (13 + 1) = 13 squared x 14 = 2366.Following this, the next number would be 17 squared x 18 = 5202.