Having trouble building a calculator
<p>I am trying to build a simple calculator to learn javascript/jquery but seem to be getting quite confused on how to make it work. Basically at the moment I dont seem to be able to update my tally correctly, instead of the numbers/values being added together in a sum they are being concatenated instead, if anyone could give me some guidance on how I can get back on the right path with this and any other advice on how to make the code more efficient then that would be great. I don't want anyone to give me the correct script just yet.</p>

<p><a href="http://jsfiddle.net/kyllle/edRk9/4/" rel="nofollow">http://jsfiddle.net/kyllle/edRk9/4/</a></p>

<p>Thanks all in advance for your advice</p>
