Let A be the set of all strings of decimal digits of length five. For example 00312 and 19483 are strings in A

How many strings in A have the digits in a strictly increasing order? For example 02357 and 14567 are such strings, but 31482 and 12335 are not

Note: It's asking how many numbers are in a strikingly increasing order in set A? Not a program to identify which numbers are satisfied by the restriction.