Question

Complete the series: 1, 3, 10, 21, 64, 129, ?, 777

Answer 1

The value of missing number (?) is equal to 388.

Step-by-step explanation:

The given series:

1, 3, 10, 21, 64, 129, ?, 777

To find, the value of missing number (?) = ?

The pattern follow:

(Previous number × 2) + 1, (Previous number × 3) + 1, (Previous number × 2( + 1, (Previous number × 3) + 1, ......

3 = 1 × 2 + 1 = 2 + 1 = 3

10 = 3 × 3 + 1 = 9 + 1 = 10

21 = 10 × 2 + 1 = 20 + 1 = 21

64 = 21 × 3 + 1 = 63 + 1 = 64

129 = 64 × 2 + 1 = 128 + 1 = 129

? = 129 × 3 + 1 = 387 + 1 = 388

777 = 388 × 2 + 1 = 776 + 1 = 777

∴ The value of missing number (?) = 388

Thus, the value of missing number (?) is equal to 388.