In this series, the 1st, 3rd, and 5th numbers double as they progress, while the 2nd. 4th, and 6th number decrease by 4. That being the case, the next 2 numbers in the series would be 24, 4.
Look at the difference between each number and the next number.
108
24
12
30!
12,14,16,18,20,22,24,26,28,30,32,34,36,38,40,42,44,46,48,50
The next number in the series 4, 12, 6, 12, 36, 18, 36
The next number in the series 4-12-6-12-36-18-36.. is 108.
The next number is the sequence 236175969, 48, 12 is 236175861.
Look at the difference between each number and the next number.
18
108
108
108
24
24
What would be the next number in this series 15 12 13 10 11 8?