UPSC Prelims 1999·GS1·science-and-technology·science and technology

In the sequence of numbers 5, 8, 13, X, 34, 55, 89, ..... the value of ‘X’ is

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  1. A20
  2. B21Correct
  3. C23
  4. D29

Explanation

The given sequence follows the logic of a Fibonacci series where each number is the sum of the two preceding numbers. Starting from the beginning: 5 plus 8 equals 13. 8 plus 13 equals 21. 13 plus 21 equals 34. 21 plus 34 equals 55. 34 plus 55 equals 89. By applying this pattern, the value of X is 8 plus 13, which equals 21. Therefore, option B is the correct answer.
science-and-technology: In the sequence of numbers 5, 8, 13, X, 34, 55, 89, ..... the value of ‘X’ is

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