Given a positive integer $n$,let $p(n)$ be the product of the non- zero digits of $n$. If $n$ has only one digit then $p(n)=n$.
Let $S=p(1)+p(2)+p(3)+\ldots+p(999)$.What is the largest prime factor of $S$?
BdMO National Secondary 2015/3
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Re: BdMO National Secondary 2015/3
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- Posts:1007
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Re: BdMO National Secondary 2015/3
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