TIL: You can tell probably glean someone's nationality by the way they count their fingers!
Anand Jagatia for BBC Future:
"…people around the world have vastly different techniques for keeping track of numbers on their hands.
For example, if you're from the UK or many parts of Europe, you probably start counting with the thumb, and finish with the pinky. While in the US, they start counting with the index finger, ending with the thumb. In parts of the Middle East like Iran, they begin with the pinky, whereas in Japan they start with the fingers extended in an open palm, drawing them in to make a closed fist….
In India, for example, they use the lines between the segments of the fingers to count. This means each digit can represent four numbers and the whole hand can represent 20. While in parts of Eastern Africa like Tanzania, among speakers of some Bantu languages, they use both hands in a symmetric way as much as possible. The number six, for example, is shown with the index, middle and ring finger of both hands. There's also the indigenous Northern Pame people of Mexico, who count on their knuckles, and the (now extinct) Yuki language in California, which used the spaces in between the fingers…
Not only can finger counting reveal where in the world you come from, it may also shed light on how we learned to understand the concept of number – as children and even as a species."