If you divide its Circumference by it's diameter
you will get pi (3.14),
o O o O
Well how do you find the CIRCUMFERENCE (C) of a CIRCLE? (distance around)
And how do you find the DIAMETER (d) OF A CIRCLE? (distance across)
O
1. fIRST FIND THE DIAMETER: You need a ruler, and a Circle. Measure straight across the center of the circle: that's the diameter
2.. SECOND USE THE CIRCUMFERENCE formula (it works, trust me).
Circumference = diameter * pi (C = d * pi)
Well what is pi? You tell me!! (I'm confused)
(pi = 3.14) IF
C = d * pi [Algebra] THEN pi = C/d (you divided both sides by d)
Try it!!
Start Here:
Measuring across a circle with a ruler-- you get 10 centimeters. (diameter)
If you GOOGLE "pi" you get 3.1415... 
WE JUST USE 3.14 = pi OK?
diameter = 10 centimeters (cm) and pi = 3.14
C = d* pi
Circumference = diameter * pi
C = 10 cm * 3.14 (do the math)
10 cm * 3.14 = 31.4 cm
SO THIS CIRCLE HAS A CIRCUMFERENCE OF 31.4 centimeters (cm)?
YES
(Why? because... you need to go back and find out)
NOW THE FUN STUFF: pi = Circumference
diameter (YES! see above)
Three CIRCLES:
#1. circumference is 6.28 cm and diameter is 2 cm
6.28 cm/2cm = 3.14
#2. circumference is 18.6 cm and diameter is 6 cm
18.6 cm = 3.14
6 cm
#3. circumference is 15.5 cm and diameter is 5 cm
15.5 cm = 3.14
5 cm
ITS A CIRCLE:
C = d * pi C / d = pi
So, who cares? Well, this is where they got pi. And it works for any circle. Pi is called a ratio because ratio means divide and you divide Circumference of a circle by its diameter to get pi.
