The Belt Around the Earth This is a classic problem (mathmatical hall of fame) from the book series TC Mits and TC Wits. Tie an imaginary belt (perhaps with rope) around the equator of the earth. Let us assume it is 25,000 miles. Make this belt so tight so that you cannot fit even a pencil or a pin under it, let alone a finger. Now add 10 feet of rope to this belt, so that it is 25,000 miles plus 10 feet. Pretend that you can distribute the rope evenly around the earth so that it is uniformly "loose" around the entire earth. How loose will the new belt be? Would a dog be able to walk under it? Could I stick my fist under it? What about a finger or a pen or pin? Vocabulary Circumference ...sample Diameter Greece ... location Intuition Irrational Logic Pythagoras ... picture ... statue Perimeter Radius Ratio Rational

• 3.1415926
• Mom I want a fancy antipasto on Sunday
• Notice that each word has the number of letters in it to make you think of 3.1415926
• Mom (3) I (1) want (4) a (1) fancy (5) antipasto (9) on (2) Sunday (6)

• The basics ... click
• The first 10,000 digits of PI ... click
• The first 50,000 digits of PI ... click
• Celebrating PI Day next Wednesday ... click
• π Poster ... click
• Find your birthday in PI ... click
• π art ... click
• Animation on wikipedia ... click
• π songs ... click
• From the exploratorium ... click
• Colorful π Art ... click
• Search for a string of numbers in π ... click

• It wasn't until 1706 that this notation, using the Greek letter seen in the above equation - often written Pi and pronounced like the English 'pie' - was introduced by William Jones (source: http://mathforum.org/isaac/problems/pi1.html)
• π (rather than some other Greek letter like Alpha or Omega) was chosen as the letter to represent the number 3.141592... because the letter π in Greek, pronounced like our letter 'p', stands for 'perimeter'. (source: http://mathforum.org/dr.math/faq/faq.pi.html)
• Here is the Greek alphabet ... click
• π Day is also Albert Einstein's birthday!

• Use string and find out that CIRC is about 3 times DIAM
• Use math and find out that it is more than 3
• Define PI and show the first 10,000 places
• Find your birthday in PI
• Contemplate the equator of the earth

My PI Poem (Steve Bergen)

Roses are Red, Violets are blue ... 3.141592

PI is a number that is mighty fine ... 653589

Practice this often until it sticks ... 79323846

Practice when you swim since there's nothing else to do ... 26433832

Let no one ignorant of geometry enter this door ... 79502884

Numbers rule the universe, Pythagoras made the decree ... 1971693

Listen up ... click

Now time for us to record!

Reference notes about the PI symbol and HTML ...
The code is ∏ for product ... & prod; (without the space)
or & and 8719;  (without the space)

for lowercase  pi (π or π) which looks better
& #960; or & pi; (without the space) 

or  for uppercase  (Π or Π) 
 & #928; or & Pi; (without the space) 
 

great reference page for HTML symbol codes is at http://www.alanwood.net/demos/ent4_frame.html

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