Ishango Bone
The Ishango bone is a tally stick, made of bone, which contains sequences of prime numbers, and some series of multiples. The bone was found in the area of the headwaters of the Nile River. The bone has three rows of notches, with the row a) below having 2 sets of numbers in excess-one format, base 10: 9,19; 21,11. Row b) is a descending series of prime numbers from 19; row c) continues the series of prime numbers, down to 5; row c) then contains multiples of 3, 4 and 5, in an example of Egyptian multiplication.
| Row | of | tally | notches | below: | ||||
| (a) | 9 | 19 | 21 | 11 | ||||
| (b) | 19 | 17 | 13 | 11 | ||||
| (c) | 7 | 5 | 5 | 10 | 8 | 4 | 6 | 3 |
Originally from Africa, this artifact now resides at the Musee d'Histoire Naturelle, Brussels, Belgium. The bone is dated from around 20,000 BC.