12 31 25 51 49 What is the next number?

Answer 1

113

------

I contend the correct answer is not 113 but:

82

Looking at the first digit of each number from one to the next...

1 3 2 5 4

this pattern emerges:

+2 -1 +3 -1 next number in series first digit will accomodate +4, first digit will be 8

Looking at each pair of each numbers digits...

1 2 | 3 1 | 2 5 | 5 1 | 4 9

this pattern emerges in the difference between the two digits of each number:

-1 +2 -3 +4 -5 next number pair in series will accomodate +6 = 82

Answer 2

12

Answer 3

82

Answer 4

80