39. The rule here is starting with the number 9, add (-6 + sequence number * 6).
9 + (-6) = 3
3 + 0 = 3
3 + 6 = 9
9 + 12 = 21
21 + 18 = 39
39 + 24 = 63
Chat with our AI personalities
The next number in the sequence 3-15-6-30-21 is -207.
28
21
If the last number is 1/3 (it should be), the next number is 5 and 1/3
The answer is 34. The full sequence is called the Fibonachi series. Your sequence is 3 5 8 13 21 3 + 5= 8 8 + 13 = 21 Therefore: 13 + 21 = 34