The Akhmim wooden tablet, often called the Cairo wooden tablet, is a document dating to 2000 BC, near the beginning of the Egyptian Middle Kingdom. It is housed in the Egypt Museum in Cairo.

The document was believed for nearly 100 years to define a unit known as a "ro" as being equal to 1/320th of a hekat, when in fact an exact computation was taking
place that requires no additional units of the hekat. The "ro" operation
was simply
as used to exactly complete the remainder fraction component of the following divisions:

fraction

identity

5/(3 ro) = 5/960

5/(7 ro) = 5/2240

10/(10 ro) = 1/320

45/(11 ro) = 45/3520

60/(13 ro) = 60/4160

The student scribe was then asked to prove his/her division by multiplying by 3, 7, 10, 11, 13, as required, to find the complete 1/64th unit. Since the student compiling
this tablet made many arithmetic errors in the duplication arithmetic, even a 2002
translation of the document did not fully recognize the exact nature of all the division
operations. The Rhind papyrus also contains one
of these problems, division by 3, leading to confusion by Gillings (1972) and others.

The importance of the tablet is that the system of Egyptian fractions may have originated in trying to divide the smallest grain units or some other units in ancient Egyptian history.

Daressy, G. "Cairo Museum des Antiquities Egyptiennes." Catalogue General Ostraca, Volume No. 25001-25385, 1901.Gillings,
R. Mathematics
in the Time of the Pharaohs. Boston, MA: MIT Press, pp. 202-205, 1972.Peet,
T. E. "Arithmetic in the Middle Kingdom." J. Egyptian Arch.9,
91-95, 1923.Vymazalova, H. "The Wooden Tablets from Cairo: The
Use of the Grain Unit HK3T in Ancient Egypt." Archiv Orientalai, Charles U.,
Prague, pp. 27-42, 2002.