If you have a stack of pennies without counting them how do you know if there is an even or odd number of them

When faced with a pile of pennies, if I need to determine whether the count is even or odd without actual counting, I understand that even numbers are divisible by 2, while odd numbers are not. I would arrange the pennies into two rows and form pairs of 2. If there's an additional penny left after pairing, this signifies an odd total; conversely, if all can be paired off, then the number is even.