text que admita solo numeros

[chalchis]

y entro los head pones esto
<script language="JavaScript">
function validar(evt)
{
evt = (evt) ? evt : event
var key = (evt.which) ? evt.which : evt.keyCode;
if (key > 47 && key < 58 || key == 8 || key == 37 || key == 39 || key == 46 || key == 9) { return true;}
else {return false;}
}
</script>


<input type="text" onKeyPress="return validar(event);">