# Check if the digits in the number are in increasing sequence in python

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Category：Languages

I was working on a problem that determines whether the digits in the numbers are in the increasing sequence. Now, the approach I took to solve the problem was, For instance, consider the number 5678.

To check whether 5678 is an increasing sequence, I took the first digit and the next digit and the last digit which is `5,6,8` and substitute in range function `range(first,last,(diff of first digit and the next to first digit))` i.e `range(5,8+1,abs(5-6))`.The result is the list of digits in the ascending order

To this problem, there is a constraint saying

`For incrementing sequences, 0 should come after 9, and not before 1, as in 7890.` Now my program breaks at the input 7890. I don't know how to encode this logic. Can someone help me, please?.

The code for increasing sequence was

``  len(set(['5','6','7','8']) - set(map(str,range(5,8+1,abs(5-6))))) == 0  ``

You can simply check if the number, when converted to a string, is a substring of `'1234567890'`:

``str(num) in '1234567890' ``