Question

1,4,5,16,17,20,21,64,65
What is the next number in this number series and how it can be.?

Answer 1

Answer:

68,69

Step-by-step explanation:

4x4= 16

4x5= 20

4x16= 64

4x17= 68

4 is multiplied with its next no's in series

Answer 2

The missing number(?) = 68.

Step-by-step explanation:

The given series are:

1, 4, 5, 16, 17, 20, 21, 64, 65

First series,

1 , 5, 17, 21, 65

The pattern follow,

+ 4, × 3 + 2, + 4, × 3 + 2, ......

4 = 1 + 4 = 5, 17 = 5 × 3 + 2 = 17,

21 = 17 + 4 = 21 and 65 = 21 × 3 + 2 = 65

Second series,

4, 16, 20, 64, ?

× 3 + 4, + 4, × 3 + 4, + 4,

16 = 4 × 3 + 4 = 16, 20 = 16 + 4 = 20,

64 = 20 × 3 + 4 = 64

Similarly,

∴ ? = 64 + 4 = 68

Hence, the value of missing number(?) is equal to 68.