you get Answer: Assuming you mean second when you say tenth the answer is 36
Explanation:
Ok so if the units digit is 1, then there are 8 posibble bigger digits: 2,3,4,5,6,7,8,9
if the units digit is 2, then there are 7 possible bigger digits: 3,4,5,6,7,8,9
and so on...
8+7+6+5+4+3+2+1+0
which equals 36
im only in 5th grade dont blame me if im wrong