Almost, just almost
We say that a number is almost increasing if for each digit of that number, either that digit is 0 or all digits to the left of it are (strictly) smaller than it. How many 4 digit numbers are almost increasing?
Details and assumptions
As an explicit example, the number \(2035\) is almost increasing.
The number \(12=012\) is a 2 digit number, not a 3 digit number.