Multiple choice

In the series, 11, 23, 43, 73, 115, 171. ..... the next term is:

  1. 238

  2. 276

  3. 243

  4. 261
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Find the pattern in differences: 23-11=12, 43-23=20, 73-43=30, 115-73=42, 171-115=56. Second differences: 20-12=8, 30-20=10, 42-30=12, 56-42=14. Second differences increase by 2 each time. Next second difference = 16, so next first difference = 56+16=72, giving next term = 171+72=243. Option C is correct.

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