It's unfortunate that we have 5 fingers.
255 if you use both hands!
More like 1023 if you also use thumbs but I prefer to use them as carry, overflow bits.
It's so natural, useful and lends well to certain numerical tricks. We should explicitly be teaching binary to children earlier.
It was only as an adult that I realised nobody around me counted this way. You are the first person I have found who talked about this method, so I am glad to find this comment of yours.
When I was a kid I relized that I can count the fives on the right hand (1 finger for each 5 on the left), which brought me to 25.
It is only when I was traveling in Asia and watched people on markets that I realized that I can use my thumb to count my 12 other finger phalanges, which brought the total to 144. You just need to know your multiplication table of 12 :)
This gives you the range 0..99. Sweeet.