The sequence of numbers you’ve provided is 1, 1, 2, 3, 4, 5, 8, 13, 21. At first glance, it may not be immediately clear that these numbers have a particular pattern. However, this sequence resembles the famous Fibonacci sequence, where each number is the sum of the two preceding ones. In the Fibonacci series, we start with 0, 1, then follow with
- 0 + 1 = 1
- 1 + 1 = 2
- 1 + 2 = 3
- 2 + 3 = 5
- 3 + 5 = 8
- 5 + 8 = 13
- 8 + 13 = 21
Each of these follows the rule perfectly. However, in your provided sequence, we notice the presence of the number 4.
To break it down:
- 1 (1 + 0)
- 1 (1 + 0)
- 2 (1 + 1)
- 3 (1 + 2)
- 4 (which doesn’t fit the Fibonacci pattern)
- 5 (2 + 3)
- 8 (3 + 5)
- 13 (5 + 8)
- 21 (8 + 13)
Hence, the number 4 is the one that does not belong in the series, as it disrupts the Fibonacci pattern. Every other number is indeed part of this well-known sequence, making the number 4 the odd one out.