YSK You can count past 1,000 on your fingers by using binary, instead of just 10

With just one hand, you can count to 31, and with both hands you can reach a whopping 1,023. This is because the placement of the held up fingers matters, rather than the amount.

It can be very useful in everyday use, being able to count to huge numbers when you don't have your phone or pen and paper nearby.