The missing number in this pattern is 18.
To understand why, let’s break the sequence down into two interleaved sequences:
- The first sequence is: 5, 10, 15, 20, 25
- The second sequence is: 3, 13, 30
The first sequence consistently adds 5:
- 5 + 5 = 10
- 10 + 5 = 15
- 15 + 5 = 20
- 20 + 5 = 25
The second sequence, however, adds 10, then 17:
- 3 + 10 = 13
- 13 + 17 = 30
If we look at the gap after 3, we see that to maintain the pattern, 3 should add 15 to reach 18:
- 3 + 15 = 18
Now the complete sequences are:
- 5, 10, 15, 20, 25
- 3, 18, 30
This way, the entire pattern flows logically and consistently. Therefore, the missing number that completes the pattern is 18.