I used the old three-finger card punches.
You get to remember that 0-3-8 is a comma.
The whole of the IBM mainframe character code (Ebcdic)is based on the card codes.

For example, the use of letters to indicate negative numbers is based on the use of the 11 hole as a minus sign, but 11 plus a number gives a letter in the range J to R.

It was possible to push a piece of 'chad' (the punched-out bits) back into a hole, if you punched it wrong. Later on, we got flashy patches to stick over the holes.

If you had a large deck, you marked it with felt-tip to find out whether the operators had dropped it and not told you. That's why IBM source decks still have sequence numbers, so you can sort the cards back into order if they are dropped.

ICL used paper tape instead - but that was more difficult to amend.