Find the missing number: 1,6,15, ? 45, 66, 91
সমাধান
সঠিক উত্তর: Option A
Pattern in the series is, +5, +9, .., .., +21, +25
So 4 is getting increased at every term addition.
Missing term in the series will be 15+(9+4)
= 15+13 = 28
