There are many surviving physical specimens of cubits rods. Many are different lengths and scales divided into different subdivisions. There are rods with 7 palm, 28 digit subdivisions (with provisions for extrapolating the cubit into 448 subdivisions) Majority of rods are of this configuration.
A cubit rod with 27 digits 20 1/4" in length, no palm divisions (Specimen #4: Turin Museum catalog #6349).
A cubit rod with 24 digits 20 5/8" in length, no palm divisions appear on this rod. (Specimen #5: Turin Museum catalog #6348)
There is a rod with 12,72 and 360 subdivisions 20 1/8 inches in length.
There are no physical specimens with 25 digit subdivisions. In my opinion any use of of a cubit with 25 digits is pure speculation. [www.egyptorigins.org]
Extrapolating cubit lengths and according to Petrie's figures:
G1, the Kings Chamber sarcophagus is 90" long divided by 5 = 18" as a possible cubit length.
G2, the sarcophagus is 103.68 (2592/25) inches in length, divided by 5 = (2592/125) 20.736 inches.
Problem 50. A circular field has diameter 9 khet. What is its area. The written solution says, subtract 1/9 of of the diameter which leaves 8 khet. The area is 8 multiplied by 8, or 64 setat.
There is no extrapolation of pi by the Ancient Egyptians.[www.math.buffalo.edu] area of a circle, and <[www.math.buffalo.edu]; calculating surface area of a hemisphere.
They simply say subtract 1/9 of the diameter and square the result. All extrapolations regarding pi are ours, The Ancient Egyptians made no notations of pi anywhere. Unfortunately, when you say Egyptian pi you are actually speaking of an extrapolated value, based on our understanding and methods of making circular calculations, not theirs.