Blog #624 for PI Day

Happy PI Day!!!

Yes, it is March 14 2019!!!  Or, that might be 3/14/2019 – or just with the month and day – 3/14 – or 3.14

And, yes, it tends to be more of an American ‘thing’ as Much of the world puts the day first, then the month, then the year, so in Europe today it is:  14/3/2019 or 14.3.2019. But it is ‘cooler’ to have 3.14 as the day.

So, what is PI?  (π)

Well, “Defined as the ratio of the circumference of a circle to its diameter, pi, or in symbol form, π, seems a simple enough concept.”

So, as the ancients made circles, they compared the diameter to the circumference – and found the circumference was a little more than three times the diameter.  Okay, how much more? Well, about 1/7th more – approximately.

The mathematicians tried to work it out.  They drew a circle and put a box (square) inside the circle and one on the outside of the circle.  If the area of the box was (say) 3 of the inside circle and the area of the box of the outside figure was (say) 3.2, they got a good idea that the circumference was about 3.1.  By putting other figures inside and outside the circle (like putting a hexagon or octagon or a decagon) inside and outside the circle, they got closer to the real measurement – but not perfectly.  They also found the area of the circle was something like this value (say) 3.14 times the radius of the circle squared.

With better measurements and techniques, the universal value of 3.14 was acceptable.  

But, those ancient mathematicians were baffled.  All they knew were ‘real’ numbers that could be whole numbers and fractions (like 355 divided by 113 – which is 3.14159).  I learned (memorized) this rhyme: “Sir, I send a rhyme excelling In sacred truth and rigid spelling” which is 3.14169265358.

Pi was finally understood to be an ‘irrational’ number – one that really knew no bounds.  It didn’t repeat like ⅓ (as 0.33333 – repeating) or 1/7 (as 0.142857 – repeating). How could God have created a world with a number that was irrational?  It didn’t really make sense (at least to the ancient mathematicians).

Needing a name for this eventually ‘p’ for perimeter of a circle became pi!!

Taking the concept a little farther, Pi Day (3.14) has become a day of math and science.  I have friends that shoot off rockets for Pi Day, (although they generally shoot the rockets on the weekend before March 14, if that day is in the middle of the week).

Of course there are the takeoffs on this.  Pie as compared to Pi. The area of circles is “pi r square” – but every person knows that pies are round!!   

So, on this March 14th – think of Pi in your life!!!  Wheels are circles, plates are (generally) circles, cups are (generally) circles on the tops (or cylinders).  

What do you think?


(I was working with one of my tutees a few weeks ago with angles.  She had learned angles in degrees, but the problem had the angles in radian measure – so where 90 degrees was pi/2 in radian measure.  Then we were finding the sine, cosine using radian measures. It took some time to get the concept!!!)

Posted by Bruce White

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