The missing number in the series 5, 6, 9, 14, 21 is 30.
Based on the reference provided, the series follows a pattern where the difference between consecutive numbers increases. The reference indicates that 21 + 9 = 30, suggesting that the difference between 14 and 21 (which is 7) is then incremented by 2 (to become 9), and added to 21 to find the next number. Let's illustrate the pattern:
| Number | Difference from Previous Number |
|---|---|
| 5 | - |
| 6 | 1 (6-5) |
| 9 | 3 (9-6) |
| 14 | 5 (14-9) |
| 21 | 7 (21-14) |
| 30 | 9 (30-21) |
Therefore, the completed series is 5, 6, 9, 14, 21, 30.
