How do I replace newlines only between numbers and a sentence?

I want to remove newlines in some special cases. I have this text:

0 
15.239 
23.917 
 Reprenem el debat que avui els oferim entorn de les perspectives d'aquest dos mil set. &lt;ehh&gt; Estavem parlant concretament dels temes 
30.027 
de la seguretat mundial 
 una miqueta 
de la intervencio
33.519 
que

And I want to replace newlines between a number and some text as so:

0 
15.239 
23.917 Reprenem el debat que avui els oferim entorn de les perspectives d'aquest dos mil set. &lt;ehh&gt; Estavem parlant concretament dels temes 
30.027 de la seguretat mundial una miqueta de la intervencio
33.519 que

I want only to erase the new lines between numbers and a sentence.

Can anyone help me?

Solution

An awk:

awk '/^[0-9]+\.[0-9]+/{printf "\n"}{printf $0}' filename

For handling DOS line breaks:

awk '{sub(/\r$/,"")}/^[0-9]+\.[0-9]+/{printf "\n"}{printf $0}' filename

Demo:

$ awk '{sub(/\r$/,"")}/^[0-9]+\.[0-9]+/{printf "\n"}{printf $0}' filename                        

0 
15.239 
23.917  Reprenem el debat que avui els oferim entorn de les perspectives d'aquest dos mil set. &lt;ehh&gt; Estavem parlant concretament dels temes 
30.027 de la seguretat mundial  una miqueta de la intervencio
33.519 que que

Explained code:

{sub(/\r$/,"")} : Delete DOS linebreaks.
/^[0-9\.]+/{printf "\n"}: When the line begins with a number/dot combination, print just a carriage return an continue with record processing.
{printf $0} : For the remain record or the ones not started by numbers just prints $0 without line breaks.
At the end , placing the carriage return just before the numbers and ignoring the rest makes the trick.