The next number in the sequence is 5.
This sequence is a part of the Fibonacci series, where each number (after the first two) is the sum of the two preceding ones. In this case:
- 55 is the sum of 34 and 21
- 34 is the sum of 21 and 13
- 21 is the sum of 13 and 8
- 13 is the sum of 8 and 5
Since the last two numbers in this sequence are 8 and 5, the next number is calculated by subtracting 5 from 8, giving us 5 as the next number in the sequence.