Complete the series:15, 24, 35, 48, 63 ______

The correct answer is Option (1) → 80

The differences between the terms are 9, 11, 13, 15: consecutive odd numbers, each 2 more than the last.

• Next difference \(=15+2=17\)

• Next term \(=63+17=80\)

The terms are also one less than the squares 16, 25, 36, 49, 64, so the next is \(9^2-1=80\).