Re: count zeros in a number

• To: mathgroup at smc.vnet.net
• Subject: [mg121811] Re: count zeros in a number
• From: Peter Pein <petsie at dordos.net>
• Date: Mon, 3 Oct 2011 04:23:10 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• References: <j69104\$rda\$1@smc.vnet.net>

```Am 02.10.2011 08:40, schrieb dimitris:
> 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.
>
> Dimitris
>

Using pattern matching makes this an easy one :-)

In[1]:= TrailingZeros[n_Integer] :=
IntegerDigits[n] /. {___, Except[0], z: ((0) ...)} :> Length[{z}]

TrailingZeros[24^24 55^55]
Out[2]= 55

```

• Prev by Date: Re: count zeros in a number
• Next by Date: Re: count zeros in a number
• Previous by thread: Re: count zeros in a number
• Next by thread: Re: count zeros in a number