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Re: count zeros in a number

  • To: mathgroup at smc.vnet.net
  • Subject: [mg121800] Re: count zeros in a number
  • From: DrMajorBob <btreat1 at austin.rr.com>
  • Date: Mon, 3 Oct 2011 04:21:11 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <201110020636.CAA28027@smc.vnet.net>
  • Reply-to: drmajorbob at yahoo.com

n = 24^24*55^55

6998705566601499878519159087153235987310926417579055430641039765858300\
72320000000000000000000000000000000000000000000000000000000

IntegerDigits[n] /. {__, zeroes : 0 ..} :> Length@{zeroes}

55

The more complicated version:

IntegerDigits[n] /. {__, zeroes : Longest[0 ..]} :> Length@{zeroes}

55

isn't necessary, because __ is taken to mean Shortest[__] by default.

Bobby

On Sun, 02 Oct 2011 01:36:47 -0500, dimitris <dimmechan at yahoo.com> wrote:

> Hello.
>
> Consider e.g. the number 24^24*55^55.
> This number ends with exactly 55 zeros as the following demonstrate
>
> In[201]:= Mod[24^24*55^55, 10^55]
> Mod[24^24*55^55, 10^56]
>
> Out[201]= 0
> Out[202]= 20000000000000000000000000000000000000000000000000000000
>
>
> What I want now is a way to count the zeros that a number ends without
> knowing in advance this number of zeros like in the above example.
>
> Thanks in advance.
> Dimitris
>


-- 
DrMajorBob at yahoo.com



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