Pi
is the relationship of a circle's circumference to its diameter. No
matter how large or small a circle is, the proportion of the distance
around the circle to the distance across its widest part is EXACTLY
the same!
That
exact number starts off 3.14159265...and goes on for bajillions of
non-repeating digits. Because pi starts with 3.14, we celebrate Pi
Day on 3/14, or March 14th.
But
today is not that date. Why are we celebrating Casual Pi Day today?
Well,
the other name for the day gives us a hint—it's Pi Approximation
Day.
It's
hard to be exact about pi when the decimal digits go on forever (and
don't even repeat). So we have to use approximate numbers when we
actually use pi, and a really approximate way of expressing the
approximation is the fraction 22/7. And that's why today, the 22nd
day of the 7th month, is Pi Approximation Day!
Use
a calculator to see what 22 divided by 7 is. How many decimal places
match pi?
By
the way, you can get a picture of pi being all casual and summery on
a T-shirt or mug here.
Approximate,
ashmoximate!
When
we are doing mental math or solving real-life problems in our heads,
we often don't need the exact answer. Instead, we can use just an
approximation of the right answer. And we do this by
estimating—rounding off and THEN adding or multiplying or whatever
we are trying to do...
Practice
your estimation skills with these PBS games or these Gamequarium games.
Also
on this date:
