How tallies can be used to represent numbers
Perhaps the simplest way of recording numbers, tallies can be thought of as a unary number system, i.e. counting in base 1. One mark or symbol is made or drawn for each thing being counted, for example, the number 5 would be represented as five marks or symbols.
Tallies have been around for a very long time, the earliest example being the Ishango bone found in the "Fisherman Settlement" of Ishango in the Democratic Republic of Congo. [wiki] It is a mammal bone with a large number of grouped marks cut into its sides made around 20,000 years ago, it is widely believed to be the first evidence of mathematical thinking in human evolution. The meanings of the marks is debated, but it seems to indicate some awareness of counting. [cite]
Tallies are often drawn in specific orientations and groupings, making them easily identifiable at a glance. You will probably be familiar with the ‘picket fence’ tally, 4 downward strokes, and a diagonal to finish a group of five. But did you know there are other ways of tallying?
Picket fence
This method of tallying is common in Europe and North America. The position and angle of the fifth tally mark may vary, one variation is a fully horizontal line through the middle of the other four, forming a 'herringbone'. [cite]
Chinese tally
Based on the Chinese character 正 meaning right or correct. The character is made up of 5 strokes and is used not just in China, but also in Asian countries that use Chinese characters such as Japan and Korea
Box tally
This tally is used in France, Spain, and South America. A variation of this tally counting up to 10 is drawn by dotting the four corners, then drawing the four sides and both two diagonals.