Sometimes you need to count something, and there is nothing at hand to temporarily store the result. Usually, in this case, the hands themselves are used, allowing to count to 10, which is not always enough. But for burn-through programmers, the output is obvious, and I think you guessed it :)
Use the binary system! And we immediately get the opportunity to keep the number up to 32 on one hand, and up to 1024 on two hands, which should be enough in 99% of cases. Well, as additional bonuses - pumping the brain and plastic fingers.
PS: if you want to show someone the result, show the number 4 with caution.