Day 39: Heart of Mathematics

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New assignment:

Wed

4/21

Egyptian Arithmetic

Recall: Assignment for Friday: you need to revise one more time: this time including a graphic of your presentation, including at least two references. You should include any previous revisions of the proposal for full credit. This is another 10% of your project grade.
If you do not attend the poster sessions (either your own or other peoples' sessions) you will lose 10% of the total grade for each day you do not attend and participate)

Order of presentations: here are your dates for next week:

Today: What can you do with only two fingers? (All things binary!)
- Today we look at something out of the distant past: Egyptian arithmetic.
- Before we begin, any questions about the binary (base 2) card trick?
- Multiplication is accomplished through binary decomposition (successive doublings). Consider, for example, 57*63:
  
  1 63 *
  2 126
  4 252
  8 504 *
  16 1008 *
  32 2016 *
  64 too big!
  
  Now add up those rows marked with an asterix (*). You'll get the answer (3591).
- Division is also carried out in binary, but fractions make it more interesting: Why did Egyptians do things this way? (an example division problem, using binary)
- How would you divide 6 by 7?
- What kinds of problems were the Egyptians encountering?
- Unit fractions
- How would you like to do story problems like this one?!
Links:
- Wikipedia on Egyptian Multiplication
- A division example, in some gory detail.

Website maintained by Andy Long. Comments appreciated.