Help needed in a number theory problem?

Revision en2, by i_am_eating_wa_and_tle, 2017-12-28 21:10:06

PDF LINK: http://lightoj.com/volume_showproblem.php?problem=1138&language=english&type=pdf Problem link: http://lightoj.com/volume_showproblem.php?problem=1138

I think the solution is the number of 5s as prime factor in N! But how to calculate them faster.

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en3 English i_am_eating_wa_and_tle 2017-12-28 22:52:25 18 Tiny change: 'PDF LINK: ' -> '**UPD:**Got AC\n\nPDF LINK: '
en2 English i_am_eating_wa_and_tle 2017-12-28 21:10:06 2 Tiny change: 'lem=1138\nI think ' -> 'lem=1138\n\nI think '
en1 English i_am_eating_wa_and_tle 2017-12-28 21:09:45 297 Initial revision (published)