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counting and probability intermediate

Problem

How many of the factorials from 1! to 100! are divisible by 9?
Solution
To have 9 as a factor, must have two factors of 3. The first such for which this is true is 6, since . Since 9 is a factor of and is a factor of for all , the numbers are all divisible by 9. There are numbers in that list.
Final answer
95