Pi Symbol And Its Meaning – The Greek Pi Sign And Its Uses

What does the pi symbol mean and where does it come from? How did it find its way into our math books? All those questions will be answered in this extensive post about the pi sign. Here is all you need to know about pi symbol, its meaning, history and origins. 

What is the Pi Symbol? 

As the sixteenth letter in the Greek alphabet, pi comes right after the letter omicron, and is followed by the letter rho.

Like most letters in the Greek alphabet, pi is case-sensitive. However, the two symbols used to represent pi in uppercase and lowercase respectively are quite similar in appearance.

In handwritten texts, it can be difficult to distinguish between capital and small letters for pi. In fact, they are often used interchangeably in manual scripts. 

  • The symbol used to represent uppercase pi is Π
  • The symbol used to represent lowercase pi is π

In the Greek numeral system that denotes numeric value to Greek alphabets, the pi sign corresponds to a value of 80.

Pi Symbol And Its Meaning - The Greek Pi Sign And Its Uses
Pi Symbol, The Sixteenth Letter in Greek Alphabet – ©Niakris6 at ShutterStock

The Greek symbol for pi can also be found in various other ancient languages although in a slightly modified form. For example, the Gothic letter ‘pairtha’, which looks like a small hut with somewhat slanted walls, was derived from the letter pi in the Greek alphabetical system. 

Origin of the Pi Symbol 

The pi sign is said to originate from the letter ‘Pe’ in the system of the Phoenician alphabet.

Phoenician alphabet, also known as the Proto-Canaanite alphabet, is one of the oldest known writing systems, dating as far back as 1200 BC.

The Phoenician letter Pe looked somewhat like a vertically inverted image of the letter ‘C’ that we use in the modern English alphabetical system. Pe literally meant ‘mouth’ or a source of water (as in a ‘well’).

Some historians suggest that the pi symbol was originally shaped like a vertically straight line with a downward-pointing hook at the side. Over time, the ‘hook’ was extended further down till it resembled a square with one side missing (which is exactly how the uppercase pi Π looks like).

The unique thing about the pi symbol is that it is a lot more than just another letter in Greek typography. It plays a key role in mathematics, and is of paramount importance in the field of science and technology.

Meaning and Uses of the Pi Symbol/Sign

Pi denotes the irrational, never-ending number 3.14159265359…

You probably know that already. But how did this otherwise ordinary Greek letter come to represent this idea?

Here is a brief explanation.

The symbol for lowercase pi was used by primeval geographers to calculate the meandering ratio of rivers. 

The meandering ratio is defined as the actual length of a river, divided by the shortest possible distance between its source and mouth. 

When a sufficiently large set of data was analyzed, the geographers found that the average meandering ratio approached – well, you guessed it – the value of pi.

This is further supported by the fact that the two sides of the pi sign loosely depict the bends in a river whereas the Phoenician letter Pe that it stems from actually means the ‘mouth of a river’ itself.

Uses of the Lowercase Pi Symbol

The lowercase pi symbol is universally recognized as a mathematical constant, and it is truly one of its kind!

It is described as the ratio between the circumference of a circle and its diameter.

Although it is commonly approximated to a value of 3.14 or 22/7 in fractional form, the actual value of pi exceeds far beyond what humans have been able to calculate so far. 

Babylonians, Egyptians, and many other ancient civilizations made several attempts to compute the value of pi accurately. But it wasn’t until the 5th Century when a Chinese mathematician found the value of pi to seven significant figures. 

Today, supercomputers and complex algorithms allow scientists to compute the value of pi precisely to about one trillionth of a decimal place.

Some texts distinguish between pi as a letter and pi as a mathematical constant by referring to the latter as Archimedes constant.

To further assert the importance of pi in the modern world, March 14 (3/14) is internationally celebrated as Pi Day. 

Uses of the Uppercase Pi Symbol

In legal shorthand, the symbol for uppercase pi is used to refer to the ‘plaintiff.’ 

Scientists use the uppercase pi symbol to denote the osmotic pressure that develops across a semi permeable membrane in certain chemical solutions. 

This symbol is also used by mechanical engineers who study fluid dynamics. In this branch of mechanics, the pi symbol represents a viscous stress tensor.

Moreover, in the field of pure mathematics, the capital pi symbol is viewed as a product operator – a technique used to multiply the terms of a sequence in a methodical way.

How to Type the Pi Symbol in Word?

Since pi is used in numerous mathematical formulas, it is essential to know how to include the pi symbol in your documents rather than just typing its estimated value instead.

There are three different ways in which you can insert the pi symbol in documents created on a computer running on Windows. The method for typing pi in Mac is discussed later.

Method 1 – Inserting the Pi Symbol Using Unicode Text Converter

  1. Place the cursor where you want to insert the pi symbol in the document.
  2. Type the appropriate Unicode text for the pi symbol.
  • 03A0 for uppercase pi 
  • 03C0 for lowercase pi
  1. Without pressing the space bar or any other key, hold down the ‘Alt’ key and simultaneously press ‘X.’ The alphanumeric word will automatically turn into the required symbol.

Method 2 – Inserting the Pi Symbol Using Built-In Symbols

  1. Place the cursor where you want to add the pi symbol.
  2. Form the main menu displayed in Word above, select the Insert option. This will open up a new toolbar.
  3. Click on Symbols. A small window containing different symbols will pop up. If you do not see the pi sign in the symbols displayed, then click on More Symbols beneath the window. A dialog box will open up.
  4. In the ‘Subset’ bar, select the ‘Greek and Coptic’ option from the dropdown menu.
  5. Find the uppercase and lowercase pi signs in the symbols shown. Double click the required pi sign and it will be inserted in the file.
  6. Close the dialog box.

Method 3 – Inserting the Pi Symbol Using Number Pad

  1. Place the cursor where you want to insert the pi sign.
  2. Turn on the Num Lock by pressing the Num Lock key on the number pad.
  3. While holding down the ‘Alt’ key, enter the number 227 (Note: you MUST use the number pad).
  4. The symbol for lowercase pi will appear on the screen.
  5. Release the ‘Alt’ key.

How to Type the Pi Symbol in Mac?

  1. Place the cursor at the required spot.
  2. Press the Option key and keep holding it down. 
  3. Immediately press the ‘P’ key. The pi sign will be inserted into the document.
  4. Release the Option key. 

This wraps up our post about the pi symbol, its meaning and origins. If you would like to read about more Greek symbols and countless others, please visit our symbols and meanings section from the top menu.