This is a ridiculous post and I apologies for it, equally it’s super important and I feel that everyone should be aware of this insignificant and mostly obsolete skill.
When using pencil/pen/chalk to keep count, using a tally is super simple. Rather than having 20 lines to count through on the paper/floor you have 4 sets of 5 (a tally).
All you do is make a mark for each thing you’re counting but every 5th tally goes through the previous 4. That way at a glance you can count a ginormous number of marks.