Finger counting

Finger-counting, or dactylonomy, is the act of counting along one's fingers. Though marginalized in modern societies by Arabic numerals, formerly different systems flourished in many cultures, including educated methods far more sophisticated than the one-by-one finger count taught today in preschool education.

Finger-counting can also serve as a form of manual communication, particularly in marketplace trading – including hand signaling during open outcry in floor trading – and also in games such as morra.

Finger-counting varies between cultures and over time, and is studied by ethnomathematics. Cultural differences in counting are sometimes used as a shibboleth, particularly to distinguish nationalities in war time. These form a plot point in the film Inglourious Basterds, by Quentin Tarantino, and in the book Pi in the Sky, by John D. Barrow.

A person indicating a numeral to another will hold up their fingers to signal the specific number. For example, people from North America and the United Kingdom will raise their index, middle, and ring fingers vertically to signal the number 3.

For Continental Europeans, the thumb represents the first digit to be counted (number 1), as opposed to the index finger in North America and the UK. The index finger is number 2 through to the little finger as number 5. Fingers are generally extended while counting, beginning at the thumb and finishing at the little finger. For example, Europeans would use their thumb, index, and middle fingers to express the number 3, whereas in North America and the UK they would use their index, middle, and ring fingers.

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