function validateNumber(event) { 
var key = window.event ? event.keyCode : event.which;

if (event.keyCode == 8 || event.keyCode == 46
|| event.keyCode == 37 || event.keyCode == 39) { 
return true;
} 
else if ( key < 48 || key > 57 ) {
return false; 
}
else return true;
};