How can i make this shorter?

hello all,

How can i make this shorter? I need to have 15 altogether.

Thanks all.

<script type="text/javascript">
    $(document).ready(function(){
     $("#divextra1").css("display","none");
      $("#divcheckme1").click(function(){
        if ($("#divcheckme1").is(":checked"))
        {
            $("#divextra1").show("fast");
        }
        else
        {      
            $("#divextra1").hide("fast");
        }
      });
    });

    $(document).ready(function(){
     $("#divextra2").css("display","none");
      $("#divcheckme2").click(function(){
        if ($("#divcheckme2").is(":checked"))
        {
            $("#divextra2").show("fast");
        }
        else
        {      
            $("#divextra2").hide("fast");
        }
      });
    });
	
    $(document).ready(function(){
     $("#divextra3").css("display","none");
      $("#divcheckme3").click(function(){
        if ($("#divcheckme3").is(":checked"))
        {
            $("#divextra3").show("fast");
        }
        else
        {      
            $("#divextra3").hide("fast");
        }
      });
    });

    $(document).ready(function(){
     $("#divextra4").css("display","none");
      $("#divcheckme4").click(function(){
        if ($("#divcheckme4").is(":checked"))
        {
            $("#divextra4").show("fast");
        }
        else
        {      
            $("#divextra4").hide("fast");
        }
      });
    });

    $(document).ready(function(){
     $("#divextra5").css("display","none");
      $("#divcheckme5").click(function(){
        if ($("#divcheckme5").is(":checked"))
        {
            $("#divextra5").show("fast");
        }
        else
        {      
            $("#divextra5").hide("fast");
        }
      });
    });
</script>

HTML:

 

1-15
Compressed: http://pastebin.com/raw.php?i=0cGkwVSK
DEP/Compressed: http://pastebin.com/raw.php?i=CMbX5yx8

 

<script type="text/javascript">

function showHide(obj1,obj2)
{
if ($("#"+obj1).is(":checked"))
{
$("#"+obj2).show("fast");
}
else
{
$("#"+obj2).hide("fast");
}
}
</script>

call the showHide function as follow

let say

<input id="divcheckme1" name="divcheckme1" onclick="showHide('divcheckme1','divextra1')/>
<input id="divcheckme2" name="divcheckme2" onclick="showHide('divcheckme2','divextra2')/>
<input id="divcheckme3" name="divcheckme3" onclick="showHide('divcheckme3','divextra2')/>

as follows