function check_number(number_field, precision) {
	number = '';
	var dots = 0;
	if(number_field.val() != null) {
		var number_array = number_field.val().split('');
		for(var i = 0; i < number_array.length; i++) {
			if(precision) {
				if(number_array[i] == '.' && dots == 1) number_array[i] = '';
				if(number_array[i] == '.') dots++;
				if(number_array[i] != '.' && isNaN(parseFloat(number_array[i]))) {
					number_array[i] = '';
				}
			}
			else {
				if(isNaN(parseFloat(number_array[i]))) {
					number_array[i] = '';
				}
			}
		}
		number = number_array.join('');
		number_array = number.split('.');
		if(number_array.length > 1) {
			if(number_array[1].length > 2) {
				suffix = '';
				for(var i = 0; i < precision; i++) {
					suffix += number_array[1][i];
				}
				number = number_array[0] + "." + suffix;
			}
		}
		number_field.val(number);
	}
}