Pi is both amazing and highly misunderstood. Not only is it irrational but it is also one of the most useful mathematical concepts in the world.

On the surface, it is a very simple concept, but when you dig a little deeper you soon realize there is something very special about this seemingly innocuous number.

It also happens to have a long and very interesting history. Whilst the concept of it has been known for thousands of years, it was only fairly recently that the world agreed on a name for it.

It is used to stress test computers and also test the very limits of human memory. Chances are you might use it every day too.

Here we gathered some of the more interesting facts about this incredible number. Trust us when we say this list is far from exhaustive.

This is also not a 'top" list of facts.

## 1. March 14th is international Pi day

Whilst this might sound a little random at first, it's actually a funny joke - but only if you write numbers in the American format. March the 14th is, after all, 3/14 - the first 3 numbers of Pi or 3.14.

This also happens to be Albert Einstein's birthday too. Coincidence? Yes, of course, it is.

It was first 'observed' back in 1988 when Larry Shaw of San Francisco's Exploratorium Science Museum started the trend. Its popularity has grown exponentially since then, and in 2009 the U.S. Congress passed a resolution to make it official.

It states that: “The House of Representatives supports the designation of a ‘Pi Day’ and its celebration around the world … and encourages schools and educators to observe the day with appropriate activities that teach students about Pi and engage them about the study of mathematics.”

But it would have to wait until 2010 to get it's own official Google Doodle - lucky Pi!

## 2. Pi is a very old concept

The very concept of Pi is very old indeed. It was first described around **4,000 years ago** and had been figured out by the ancient Egyptians and Babylonians.

Just like today, they had figured out the ratio of the circumference of any circle to its diameter to equal, roughly, **3.14**. The size of the circle was irrelevant, you always got the same answer.

They were even integrating it into various calculations.

The very term "Pi" also comes from the Greek letter of the same pronunciation, π. But it wasn't until the 18th Century that this became common practice amongst mathematicians.

Before that, there was no agreed name for it. Many descriptors were often a literal mouthful with examples like “the quantity which when the diameter is multiplied by it, yields the circumference” being used.

Hardly efficient, to say the least.

## 3. Pi is never-ending

Whilst the approximate value of Pi is **3.14**, being an irrational number, the number of decimal places is, in fact, never-ending. This means it can't actually easily be expressed as a proper fraction with a definite end.

It also doesn't end with a repeating pattern like **1/3, or 0.33333** reoccurring. Pi, at least as far as thus far calculated, doesn't appear to have a certain number of finite decimal places.

For this reason, it just keeps going and going ad infinitum. To date, Pi has been calculated to over** 22 Trillion digits** - which is frankly an incredible achievement in its own right.

This took a computer, with 24 hard drives, over **105 days** to achieve working nonstop. Imagine how long that would take a human being!

## 4. There was a time that Pi was rounded up by law

Since Pi is never-ending, you might think we should all agree to cut it off somewhere. Surely, you might think, it might just be easier to call it just **3.14** or, say,** 3.2**?

This is precisely what an Indiana doctor tried to do in 1897. He argued that the world should just round it up for any, and all, future calculations that required it.

Dr. Edwin Goodwin actually proposed a bill to state legislature. He also copyrighted his idea and planned to charge royalties for anyone who used it in the future.

The bill was debated with the majority of delegates agreeing that any attempt to use the force of law to change a mathematical constant was inappropriate. It failed to pass.

## 5. Pi is not just a mathematical curiosity

Pi is not just a play thing for mathematicians. It is used every single day by scientists, engineers, and mathematicians for important calculations.

In fact, it is quite likely that if you deal with volumes, areas, etc. regularly there will a point where you use it yourself. In a lot of cases, these calculations can make or break a project or product.

According to Charles Dandino, an engineer at the Jet Propulsion Lab, Pi is very important indeed. “Those relationships form the basis for how stiff a structure is, how it will vibrate, and understanding how a design might fail,”

Another JPL engineer, Anita Sengupta, concurs. “In my career, pi has allowed me to calculate the size of a shield needed to enter the atmosphere of Venus and the size of a parachute that could safely land the Curiosity rover on the surface of Mars,”

But it has other everyday applications. For example, Pi is a vital component in your car or smartphones GPS to calculate your exact location on the Earth.

## 6. The more decimals, the better, apparently

Whilst it might be a fun party trick to reel off as many of Pi's decimals from memory as possible, the more you use in calculations, the better.

For small scale things, like the volume of your coffee cup, it might seem overkill, but as you scale up the size of something the more decimals you use the more accurate your calculations.

For example, if you were to just use the first 9 digits of Pi to calculate the Earth's circumference, your result would be pretty close to reality. For every **25,000 miles (40,234 km)** or so, the use of 9 digits would only give you an error of around **1/4 of an inch (0.635 cm)**.

That's pretty impressive when you think about it.

## 7. The record for reciting Pi is to 70,000 decimal places

Here's just a few pages from Rajveer Meena's evidence of his attempt for the most decimal places of Pi memorised - 70,000. Rajveer wore a blindfold throughout the entire recall, which took nearly 10 hours https://t.co/nAvsMXepKk #PiDay pic.twitter.com/mHf3OJRcXC

— GuinnessWorldRecords (@GWR) March 14, 2018

Pi is an incredibly long number, as we have seen. But have you ever wondered what the record for the longest recital of these by a human being?

As it happens the record was set in March of 2015 by one Rajveer Meena at VIT University in Vellore, India. According to the Guinness Book of World Records, Meena was able to recite Pi to an amazing **70,000** decimals places.

The feat took him more than 9 hours to complete. To help him focus (and not cheat), Meena, 21 years old at the time, was completely blindfolded too.

Seems the gauntlet has been thrown down, could you best Meena?