<input type="text" id="n1" size="12" disabled="disabled">+
<input type="text" id="n2" size="12" disabled="disabled">=
<input type="text" id="result" size="12">
<script>
var n1 = document.getElementById("n1");
var n2 = document.getElementById("n2");
var result = document.getElementById("result");
n1.value=parseInt(Math.random()*10);
n2.value=parseInt(Math.random()*10);
result.value=parseInt(n1.value)+parseInt(n2.value);
</script>