My name is melissa. I am a 9th grade student I am having trouble finding out how to do this: What is the tens digit of 0! + 1! + 2! + 3! + ... + 2000! I know how to find these, but my calculator cant go any higher than 69! Is there any way i can do this problem?

Hi Melissa,

Calculate 0!, 1!, 2!, ...What is the smallest n so that the units digit of n! is 0? What is the units digit of (n+1)!, (n+2)!,...? Why? What is the smallest m so that the tens digit of m! is 0? What is the tens digit of (m+1)!, (m+2)!,...? Why?

Cheers,
Penny

 

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