It could be 62.
12
31
38
20
The series appears to be decreasing by progressively smaller factors. Each number is obtained by dividing the previous number by a decreasing factor: 5000 divided by 5 gives 1000, 1000 divided by 5 gives 200, and 200 divided by 5 gives 40. Continuing this pattern, 40 divided by 5 gives 8, so the next number in the series is 8.
The next number is 20.
31
12
31.
The HCF of 38 and 40 is 2
38
31
38
In a series of numbers, there are rhythms that change. In the order of 100, 140, and 40, the number that would come next would be 80 because 40 should be added.
6
20
8, each number is a fifth of the last.