SOLUTION: Among all 2 digits numbers (10 to 99), You need to find out how many of those has its unit digit greater than the tens digit...?

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Question 949938: Among all 2 digits numbers (10 to 99), You need to find out how many of those has its unit digit greater than the tens digit...?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Let's work backwards.
Number starting with 9, none.
Numbers starting with 8, 1 (89).
Numbers starting with 7, 2 (78,79).
I think you see a pattern here.
N=0%2B1%2B2%2B3%2B4%2B5%2B6%2B7%2B8%2B9
N=45