Definition:Ishango Bone

Definition
The Ishango bone is a mathematical tool made from a leg bone of a baboon, dating from approximately $25 \ 000$ years ago.

It bears a system of markings which may be tally marks, but may in fact be for a more complex purpose.

It was found in $1960$ by in the  (now the ). It was discovered in the area of near the.

One row of marks contains the prime numbers between $10$ and $20$, that is, $11$, $13$, $17$ and $19$, which total $60$.

Another row contains $9$, $11$, $19$ and $21$, which also total $60$.

The third row contains marks which appear to represent a method of multiplication by means of a technique involving doubling and halving.

While it is suggested that the markings form a calendar, it is also possible that the markings are coincidental, and perhaps even just put there to make the bone easier to hold.

Also see

 * Definition:Lebombo Bone
 * Definition:Wolf Bone