Unary Numeral System - Clustering

Clustering

Marks are typically clustered in groups of five for legibility. This is similar to the practice of using digit group separators such as spaces or commas in the decimal system, to make large numbers such as 100,000,000 easier to read. The first or fifth mark in each group may be written at an angle to the others for easier distinction. In the fourth example depicted above, the fifth stroke "closes out" a group of five, and is sometimes nicknamed the "herringbone" method of counting. In Brazil and France, a variation of this system is commonly used: similar to the "herringbone" method, four marks are arranged to form a square, with the fifth mark crossing the square diagonally instead of arranging "sticks" in linear fashion.

Another example of a unary counting system clustered in counts of five is the Chinese, Japanese and Korean custom of writing the Chinese character, Korean Hanja character, or Japanese kanji character 正 which takes 5 strokes to write, one stroke each time something is added.