Multiple choice In the given series, which number is incorrect? 15, 22, 31, 42, 49, 70 49 15 22 42 67 Reveal answer Fill a bubble to check yourself A Correct answer Explanation The differences are: 22-15=7, 31-22=9, 42-31=11, 49-42=7, 70-49=21. The pattern of differences should be 7, 9, 11, 13, 15. 42+13=55, 55+15=70. Thus, 49 is incorrect.