Multiple choice

In the following series, one term is wrong. Select the answer from the given options. $105, 85, 60, 30, 0, -45, -90$

  1. $0$
  2. $30$
  3. $85$
  4. $-45$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Pattern: 105 - 20 = 85; 85 - 25 = 60; 60 - 30 = 30; 30 - 35 = -5 (not 0); -5 - 40 = -45; -45 - 45 = -90. The term 0 is wrong; it should be -5.

AI explanation

The pattern follows a difference of consecutive odd squares: 105 - 85 is 20 (5 squared minus 4 squared), 85 - 60 is 25 (6 squared minus 5 squared), and 60 - 30 is 30 (7 squared minus 6 squared). Applying this to the next term, 30 minus 34 (8 squared minus 7 squared) gives -4, meaning the term incorrectly listed as 0 should be -4.

Keep practicing — related questions