Study Guide: Quiz 3
Ancient Egypt
Note: This is a study guide. The quiz will consist of three or four questions covering the material below. If you understand the ideas and facts in the non-computational questions and can work through the computational problems, you will be well prepared.
Part 1: Quiz-Style Questions
- Using ancient Egyptian techniques, multiply 22 by 70.
- Using ancient Egyptian techniques, divide 132 by 12.
- Using the method of false position: A quantity and its 1/7 added together become 19. Find the quantity.
- Here is a problem similar to one from the Rhind Papyrus: A circular field has diameter 18 khet. What is its area? The solution was: "Take away thou 1/9 of it, namely 2; the remainder is 16. Make thou the multiplication 16 times 16; becomes it 256; the amount of it, this is, in area 256 setat." (A khet is a unit of length. A setat is a unit of area, equal to one khet squared.) Find the formula for the area of the circle that the scribe would have obtained by starting with a circle of diameter d instead of diameter 18. (Hint: Start by taking away 1/9 of the diameter, that is d/9.) Give your final formula in terms of d only.
- We know the area of a circle is π times the radius squared: Area = πr². Use your work in Problem 4, remembering that d = 2r (the diameter is twice the radius), to interpret the Egyptian calculation as an approximation of π. Express this approximation as a fraction. (You do not have to perform the final multiplications. For instance, 23/(66×34) is an acceptable format.)
- What two arithmetic operations form the basis of most Egyptian computations? Give an example of how each is used in Egyptian calculations.
- Explain in 2–3 sentences why the doubling-and-adding method works. (Hint: any whole number can be expressed as a sum of distinct powers of 2.)
- A part of the Rhind Mathematical Papyrus table of division by 2 follows:
2 / 11 = 1/6 + 1/66
2 / 13 = 1/8 + 1/52 + 1/104The calculation of 2 / 13 is given as follows:
1 13 1/2 6 + 1/2 1/4 3 + 1/4 1/8 1 + 1/2 + 1/8 1/52 1/4 1/104 1/8 Since 1 + 1/2 + 1/4 + 1/8 + 1/8 = 2, we have 2 / 13 = 1/8 + 1/52 + 1/104.
Following this method, perform the calculation for 2 / 11 to verify that 2 / 11 = 1/6 + 1/66.
(Problem adapted from Victor J. Katz, A History of Mathematics)
- Using ancient Egyptian multiplication techniques and the 2/n table, verify that 11 × (1/6 + 1/66) = 2.
(Problem adapted from Victor J. Katz, A History of Mathematics)
- Give an approximate timeline (century is fine): When was the Rosetta Stone created, and when was it deciphered?
- Name at least two of the three types of Egyptian writing shown on the Rosetta Stone, and explain why its discovery was important for history.
- What is the Rhind Mathematical Papyrus? In which century was it written, and what was its purpose?
- Judging from the Rhind and Moscow papyri, how was mathematics learned and transmitted in Ancient Egypt?
- Recall that Problem 79 of the Rhind Papyrus, which involved adding 7 + 7² + 7³ + ... + 7⁶, can be interpreted as theoretical. What makes this "theoretical" rather than "practical"?
- The following is a paragraph from the book "The Universal History of Numbers" by Georges Ifrah: "Another example of high numbers is from a statue from Hieraconpolis, dating from 2800 BCE, where the number of enemies slain by a king called KhaSeKhem is shown as X by the following sign." You need to find X, that is, the number of enemies slain from the hieroglyphic below. It will come in handy to read how the book continues: "Early examples show rather irregular outlines and groupings of the signs," given that our example shows such an irregular grouping.
Hieroglyphic inscription from Hieraconpolis (c. 2800 BCE)
Part 2: Reflection Questions
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Why powers of 2 in the Egyptian algorithm?
The Egyptian multiplication method relies on writing the multiplier as a sum of distinct powers of 2.
Now try to imitate this idea using powers of 3, but restrict yourself to sums of distinct powers of 3 (so each power may be used at most once).
(a) Try to compute 18 × 6 using this restriction. (Can you write 6 as a sum of distinct powers of 3? What about 18?)
(b) Explain clearly why this “powers of 3” version does not give a uniform algorithm for all multipliers.
(c) What extra feature would you need to add to make a base-3 version work for all numbers?
(d) State the key advantage of using powers of 2 in the Egyptian method. - Write your own definition of "measuring a segment."
- The "scissor congruence" slides hint that the area of polygonal shapes can be defined by cutting and rearranging the resulting pieces. What does this tell you about area?
- The cube-vs-pyramid demonstration question: Does sand-filling count as a proof? Explain what would have to be added (if anything) to make it "mathematical."
- Your view on Problem 79 of the Rhind Papyrus—practical or recreational? What would convince you it's still practical, and what would convince you it's recreational?
- Compare Egyptian multiplication with the multiplication you learned in school. Which is easier or harder for students to learn, and why?
- Looking at the Rhind and Moscow papyri problems: they're practical (bread, beer, pyramids, grain). What does this tell you about who was doing mathematics and why?
Part 3: Challenge Problems
- Imagine you are an Egyptian scribe. Write clear step-by-step instructions (in English) to compute the volume of a square pyramid with side 9 and height 9. (Hint: Follow the ideas of Problem 14 of the Moscow Papyrus.)
- Deduce algebraically the volume formula of a truncated square pyramid and then think about the tools and concepts you use. Which of those appear (or do not appear) in the Egyptian sources we discussed?
Quiz Problem Rubric
| Points | Criteria |
|---|---|
| 3 | Correct answer with reasoning/work shown |
| 2 | Partially correct with some reasoning shown |
| 1 | Correct answer without reasoning/work OR significant attempt with some understanding |
| 0 | Incorrect or blank |
Notes
- For computational problems: "reasoning/work" = steps shown
- For conceptual problems: "reasoning" = explanation given
- Round partial credit up when in doubt