series

Question

1, 9, 25, 49, ?, 121. What will come at the place of question mark ?
A.100
B. 91
C. 64
D.81

Answer 1

$ 1 + (4 \times 2) = 9 $

$ 9 + (4 \times 4) = 25 $

$ 25 + (4 \times 6) = 49 $

$ \mathbf{49 + (4 \times 8) = 81} $

$ 81 + (4 \times 10) = 121 $

Answer 2

Given series is a square of odd numbers;

• $1^2=1$
• $3^2=9$
• $5^2=25$
• $7^2=49$
• $9^2=81$
• $11^2=121$

So option (D) is correct.