Re: discrete math, how many zeroes in 125!
- To: mathgroup at smc.vnet.net
- Subject: [mg13467] Re: discrete math, how many zeroes in 125!
- From: "Allan Hayes" <hay at haystack.demon.cc.uk>
- Date: Sun, 26 Jul 1998 02:33:30 -0400
- References: <6p6rjm$5lk@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Timothy Anderson wrote in message <6p6rjm$5lk at smc.vnet.net>...
>how can I solve this problem by counting the factors of 2 and 5 without
>doing each factor individually? thanks for any real quick help! Tim
>
I assume that you mean the zeroes at the end. Here are two ways - I
change 125 to 1250 to ccompare speeds
Min[Cases[FactorInteger[1250!], {2|5, n_}->n]]//Timing
{1.48 Second, 312}
Position[Reverse[IntegerDigits[1250!]],Alternatives@@Range[9],
{1},1][[1,1]]-1//Timing
{0.28 Second, 312}
-------------------------------------------------------------
Allan Hayes
Training and Consulting
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http://www.haystack.demon.co.uk
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