January 29, 2009
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"I never failed once. I invented the light bulb. It
just happened to be a 2,000-step process."
-Thomas Edison
(after he was asked about his 2,000 “failed” attempts!)
January 29, 2009
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• Another homework note
• Section 2.3 (cont’d) – bases
• Exploration 2.9 – more bases
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Homework note
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Since you will be teaching math, it’s vital that
you write math correctly. What’s wrong
with this:
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Ex: Add 5 and 7, then divide the result by 4.
5 + 7 = 12/4
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2.3 (cont’d)
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Our class Alphabitia system is a “base 5”
system.
Typical notation for base 5:
instead of A, B, C, D, A0, AA, etc.,
write 15, 25, 35, 45, 105, 115, etc.
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2.3 (cont’d)
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• When you see “3215”, say
“three-two-one base 5”
• Let’s count in base 5:
1, 2, 3, 4,
10, 11, 12, 13, 14,
20, 21, 22, 23, 24,
30, 31, 32, 33, 34,
40, 41, 42, 43, 44,
100, 101, 102, 103, 104,…
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2.3 (cont’d)
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Ex: Explain your thought process for these.
a) Convert 1235 into our usual (base 10)
numbers.
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b) Convert 16710 into base 5.
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2.3 (cont’d)
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2.3 (cont’d)
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As you explore various bases, think about
how they are similar to base 10.
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Can you see why some children have trouble
learning the base 10 system?
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Exploration 2.9
• You will learn and practice with base 6,
base 2 and base 16.
Base 2:
• Important in computer science
• Also known as “Binary” numbers
Base 16:
• Important in computer science, too!
• Also known as “Hexadecimal” numbers
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Exploration 2.9
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Base 6: just another base that can be used
(I can’t see any particular reason why 6 was
chosen here…)
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Exploration 2.9
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• Read the introduction (pg 43).
• Do Part 1 #1a.
• Do Part 1 #2 (try this by yourself first, then
discuss with your table)
Repeat for Base 2 and Base 16 (typos in base
16 section)
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Questions?
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Exploration 2.9
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Work on Part 3: #2 & 3
and Part 4: #1, 2 & 4
(these are due on Tuesday)
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Homework
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• Read textbook pgs 109 – 118
• Do the textbook problems listed online
• Exploration 2.9
Part 3: #2 & 3
Part 4: #1, 2, 4
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