Today, March 14, is Pi Day – a day that celebrates the number 3.141593. That number is the ratio between any circle’s circumference and its diameter.
Why is March 14th Pi Day? Because March 14th is 3/14, which is the start of 3.141593. Get it?
Even if you don’t use Pi much these days, you probably remember it from your high school geometry class, when you learned to use it to calculate either the area or the circumference of a circle.
The interesting thing is, Pi can be used to make a rough estimate of the quantity of precious metals that are contained in cylindrical objects. Imagine you have hundreds of scrap metal bars containing silver alloy left over from your manufacturing process. Before you send them off to the best silver refiners to get the best prices on your silver-bearing scrap, you want to estimate how much money you stand to make.
Let's say you know each bar contains 60% silver. Let’s also say that it is 2” in diameter and 4” tall. To make an estimate of how much silver in in the bar, you first find the volume of the cylinder. To do that, you multiply the area of Pi x R2 (Pi times the radius squared) to determine the area of the base of the cylinder. For your 2” diameter bar, that comes out to be 3.14 square inches. You then multiply that times the 4” height of the cylinder; that tells you that the volume of the bar is 12.56 cubic inches. Since you estimate that 60% of the bar is silver, you can figure that 60% of its volume – or about 8 cubic inches – is silver.
You could also weigh the bar and say that 60% of that weight is silver, and figure out how much silver you have in troy ounces. But what the heck, we want to do things the mathematical way on Pi Day, right?
We hope you find 3.141593 ways to enjoy Pi Day.
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