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 Curious Consecutive Cyphers II (Posted on 2009-02-23)
A positive integer T is defined as a factorial tail if there exists a positive integer P such that the decimal expansion of P! ends with precisely T consecutive zeroes, and (T+1)th digit from the right in P! is nonzero.

How many positive integers less than 1992 are not factorial tails?

 No Solution Yet Submitted by K Sengupta No Rating

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 re(2): Computer Solution | Comment 4 of 7 |
(In reply to re: Computer Solution by Charlie)

By direct calculation in UBASIC the factorials of 124 and 125 have 28 and 31 terminal zeros respectively:

`?!(124):?!(125) 1506141741511140879795014161993280686076322918971939407100785852066825250652908790935063463115967385069171243567440461925041295354731044782551067660468376444194611004520057054167040000000000000000000000000000`
` 188267717688892609974376770249160085759540364871492425887598231508353156331613598866882932889495923133646405445930057740630161919341380597818883457558547055524326375565007131770880000000000000000000000000000000`

 Posted by Charlie on 2009-02-23 12:45:50

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