Multiple choice

In the following number series, two numbers have been put within brackets. Select the most appropriate option for these numbers in relation to their inclusion in the series. $1, 9, 25, 49, (81), 121, 169, (215), 289$

  1. Both the bracketed numbers are incorrect.

  2. The first bracketed number is incorrect and the second is correct.

  3. The first bracketed number is correct and the second is incorrect.

  4. Both the bracketed numbers are correct.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The series is squares of odd numbers: 1²=1, 3²=9, 5²=25, 7²=49, 9²=81, 11²=121, 13²=169, 15²=225, 17²=289. First bracketed number 81 is correct (9²). Second bracketed number 215 is incorrect (should be 225, which is 15²).

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