Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: Egypttian and Greek sqare root
Replies: 9   Last Post: Dec 13, 2012 8:17 PM

 Messages: [ Previous | Next ]
 Milo Gardner Posts: 1,105 Registered: 12/3/04
Re: Egypttian and Greek sqare root
Posted: Dec 2, 2012 5:30 PM

D. MIDDLE KINGDOM MIDDLE ERA SQUARE ROOT Gillings called his view of the Egyptian method an Aha problem, not disclosing precise scribal link to the Berlin Papyrus and other texts.

(omitting long discussion)

2. The Middle Kingdom Egyptian era's actual square root method was found by discussing the square root of 6

that scaled (6 x 6/6)^1/2 = (36/6)61/2 = 6(1/6)^1/2, an incorrect guess.

Scribes had scaled inverse aspect equivalent to the Berlin Papyrus method in another scaled manner

A Nov. 2012 decoded method approximated the square root of 6 in terms of s

(Q+ R)^2 + E2 and (2 + 2/5 + 1/20)^2

given that:

[6(2/5]'^2 = [12/5]^2 = [2 + 2/5]^2 = (4 + 4/5 + 4/5 + 4/25) = (5 + 15/25 + 4/25 = 5 + 19/25)

searched for a E1 = 4/25 correction that estimated the square root value as

(2 + 2/5 + 1/20)*2 = 5 + 19/25 + 4/5 + 81/400 = 6 + 1/400

with E2 = 1/400

3. The Egyptian rational number method was copied by Greek in the 2nd century BCE. The Greek method solved the square root of 164 and other problems.

For example the square root of 2, connected to the earlier square root of 6 and 1/64 may be interesting to review:

a. 2^1/2 approx. by (1 + 2/5)^2 = ( 1 + 24/25) = understated error E1 = 1/25

the scribe considered

1/5(24/24) = 48/120 = (40 + 5 + 3))/120 = 1/3 + 1/24 + 1/40)

and could have replaced 1/40 with 1/32, as the square root of 164 recommended showed

2^1/2 approx = (1 + 1/3 + 1/24 + 1/32)^2 with E2 = not enough

or,

2^1/2 approx = (1 + 1/3 + 1/24 + 1/30)^2 with E2 = again, not enough

thus,

2^1/2 was likely approx by (1 + 1/3 + 1/24 + 1/28)^2 with E2 = about right

E. CONCLUSION: Egyptian and Greek square root exactly solved squared rational numbers 4, 9, 16, 25, .... by an inverse proportion and other steps. The square root method accurately estimated irrational numbers 2, 3, 5, 6, ... and found a quotient (Q) by the inverse method and estimated a remainder (R), in unit fractions, by a subtractive method. The scribe kept in mind the initial rational number error amount (E1), while searching for a smaller irrational error amount (E2). The method's final step squared (Q + R) and determined rational unit fraction roots, plus irrational errors(E2)in proofs.

That is scribes focused upon were remainders(R). Initial remainders were often estimated in n/5 parts such that n/5 was scaled by 24/24 = 24n/120 as discussed by:

1/5(24/24) = 24/120 = (20 + 3 + 1)/120

2/5(24/24).= 48/120 = (40 + 5 + 3)/120

3/5(24/24) = 72/120 = (60 + 8 + 3 + 1)/120

4/4(24/24) = 96/120 = (80 + 8 + 5 + 3)/120

and other partitions.

as Ahmes and earlier Middle Kingdom scribes scaled a volume unit hekat to (64/64) in terms of binary quotients and remainders scaled by (5/5) to 1/320 (ro) of a hekat.

Initial estimated square root of N statements used quotient (Q) in the form

(Q + n/5)^2

The raw square root data was processed in shorthand formats that considered a rational error E1 that scribes reduced to a lower acceptable error E2.

A broadly defined historical method (found by Occam's Razor, and historical data) will be posted here. A finalized, but not final, methodology will describe selections of (irrational) errors E2 associated with adding or subtracting from the last term (1/40, most often, and as I suspect, at other times 1/120).

Q.E.D.

Math Forum discussions; Why Study Egyptian Fractions

Planetmath Remainder Arithmetic entry;

Planetmath Kahun Papyrus entry.
Bibliography

1
A.B. Chace, Bull, L, Manning, H.P., Archibald, R.C., The Rhind Mathematical Papyrus, Mathematical
2
Marshall Clagett Ancient Egyptian Science, Volume III, American Philosophical Society, Philadelphia, 1999.
3
Richard Gillings, Mathematics in the Time of the Pharaohs, Dover Books, 1992.
4
H. Schack-Schackenburg, "Der Berliner Papyreys 6619", Zeitscrift fur Agypyische Sprache , Vol 38 (1900), pp. 135-140 and Vol. 40 (1902), p. 65f.

Date Subject Author
11/27/12 Milo Gardner
11/30/12 Milo Gardner
11/30/12 Milo Gardner
12/1/12 Milo Gardner
12/2/12 Milo Gardner
12/3/12 Milo Gardner
12/3/12 Milo Gardner
12/7/12 Milo Gardner
12/8/12 Milo Gardner
12/13/12 Milo Gardner