The Lahun Mathematical Papyri is an ancient Egyptian mathematical text. It forms part of the Kahun Papyri, which was discovered at El-Lahun by Flinders Petrie during excavations of a workers' town near the pyramid of the 12th dynasty pharaoh Sesostris II. The Kahun Papyri are a collection of texts including administrative texts, medical texts, veterinarian texts and six fragments devoted to mathematics. The mathematical texts most commented on are usually named:
Lahun IV.2 : This fragment contains a table of Egyptian fraction representations of numbers of the form 2/n. A more complete version of this table of fractions is given in the Rhind Mathematical Papyrus.
Lahun IV.3 contains numbers in arithmetical progression and a problem very much like problem 40 of the Rhind Mathematical Papyrus. Another problem on this fragment computes the volume of a cylindrical granary. In this problem the scribe uses a formula which takes measurements in cubits and computes the volume and expresses it in terms of the unitkhar. Given the diameter and height of the cylindrical granary:
Lahun LV.3 contains a so-called aha problem which asks one to solve for a certain quantity. The problem resembles ones from the Rhind Mathematical Papyrus.
Lahun LV.4 contains what seems to be an area computation and a problem concerning the value of ducks, geese and cranes. The problem concerning fowl is a baku problem and most closely resembles problem 69 in the Rhind Mathematical Papyrus and problems 11 and 21 in the Moscow Mathematical Papyrus.
The Lahun papyrus IV.2 reports a 2/n table for odd n, n = 1, , 21. The Rhind Mathematical Papyrus reports an odd n table up to 101. These fraction tables were related to multiplication problems and the use of unit fractions, namely n/p scaled by LCM m to mn/mp. With the exception of 2/3, all fractions were represented as sums of unit fractions, first in red numbers. Multiplication algorithms and scaling factors involved repeated doubling of numbers, and other operations. Doubling a unit fraction with an even denominator was simple, divided the denominator by 2. Doubling a fraction with an odd denominator however results in a fraction of the form 2/n. The RMP 2/n table and RMP 36 rules allowed scribes to find decompositions of 2/n into unit fractions for specific needs, most often to solve otherwise un-scalable rational numbers and generally n/p by /p + 2/p. Decompositions were unique. Red auxiliary numbers selected divisors of denominators mp that best summed to numerator mn.
