Ragazzi devo fare una calcolatrice in php.

Ho fatto di questo esercizio la parte grafica ma come faccio a far visualizzare sul text il numero relativo al tasto che premo?

Ecco il codice




<input type="text" class="text" name="display" value="display" maxlength="400" />




<td>
<input type="submit" class="submit button" name="1" value="1" />

</td>
<td>
<input type="submit" class="submit button" name="2" value="2" />

</td>

<input type="submit" class="submit button" name="3" value="3" />




<td>
<input type="submit" class="submit button" name="4" value="4" />

</td>
<td>
<input type="submit" class="submit button" name="5" value="5" />

</td>
<input type="submit" class="submit button" name="6" value="6" />




<td>
<input type="submit" class="submit button" name="7" value="7" />

</td>
<td>
<input type="submit" class="submit button" name="8" value="8" />

</td>
<input type="submit" class="submit button" name="9" value="9" />




<input type="submit" class="submit button" name="+" value="+" />
<input type="submit" class="submit button" name="-" value="-" />
<input type="submit" class="submit button" name="X" value="X" />




<input type="submit" class="submit button" name="/" value="/" />
<input type="submit" class="submit button" name="=" value="=" />
<input type="submit" class="submit button" name="." value="." />






<?php


?>