function positiveNumeric(elem){
	$(elem).keypress(function(event) { 
		/* 
		 * Backspace, tab, enter, end, home, left, right
		 * We don't support the del key in Opera because del == . == 46. 
		 */ 
		var controlKeys = [8, 9, 13, 35, 36, 37, 39]; 
		/*
		 * IE doesn't support indexOf
		 */
		var isControlKey = controlKeys.join(",").match(new RegExp(event.which)); 
		/*
		 * Some browsers just don't raise events for control keys. Easy.
		 * e.g. Safari backspace. 
		 */
		if (!event.which || // Control keys in most browsers. e.g. Firefox tab is 0 
			(49 <= event.which && event.which <= 57) || // Always 1 through 9 
			(48 == event.which && $(this).attr("value")) || // No 0 first digit 
			isControlKey) { // Opera assigns values for control keys. 
			return; 
		} else {
			event.preventDefault(); 
		} 
	}); 							
}