**Question: **Do you know the missing number in the given series? 10, 11, 12, 13, 14, 15, 16, 17, 20, 22, 24, ___ , 100, 121, 10000

**Answer:**

The missing number is 31.

The pattern is - Sixteen in the base n for n = 16, 15, ..., 2.

16 in the base 16 = 10

16 in the base 15 = 11

16 in the base 14 = 12

16 in the base 13 = 13

16 in the base 12 = 14

16 in the base 11 = 15

16 in the base 10 = 16

16 in the base 9 = 17

16 in the base 8 = 20

16 in the base 7 = 22

16 in the base 6 = 24

16 in the base 5 = 31

16 in the base 4 = 100

16 in the base 3 = 121

16 in the base 2 = 10000

Thus, the complete series is - 10, 11, 12, 13, 14, 15, 16, 17, 20, 22, 24, 31, 100, 121, 10000