Output from PHP to form

[lucerias]

I have created a form like below, after i click on the generate button, it will run the generate.php and generate a new sum based on the input, Number. Finally i want to display the sum back in the field of the previous html form field. What code should i include in the php to ask it return back and pass the value to that page. Thank you.

<form action="Generate.php" Method=POST>
<table width="100%" border="0" cellspacing="0" cellpadding="0">    
<tr>
<td width="20%">Number:</td>
<td width="30%"><input name='Number' type="text" tabindex='3' size='10' maxlength='17' value="Enter here">&nbsp<b>kg</b></td>
</tr>

[fenway]

You just need to echo the variable in the value attribute of your input field.