The Pi symbol is surely one of the most interesting symbols in the Greek alphabet. But what does it mean and how is it used in science? Here is all you need to know about the Pi symbol, the sixteenth letter in the Greek alphabet, its meaning, origins and uses.

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**Greek Pi Symbol – Origin and History**

Pi (uppercase Π, lowercase π and ϖ; Greek: πι) is the 16th letter of the Greek alphabet. The Pi symbol essentially represents the sound [p].

Just like the rest of the Greek alphabet letters, Pi is also used in the Greek numeral system. It has a numerical value of 80.

The Greek Pi letter is thought to be a derivation of the Phoenician letter Pe. Subsequently, there are also other letters based on the Greek Pi, such as the Gothic pairthra (𐍀), Coptic Pi (Ⲡ, ⲡ), and Cyrillic Pe (П, п).

The uppercase Pi sign that we know today is actually considered a modified or the final version. It has an early form that looked almost similar to the uppercase Gamma (Γ), only with a small hook on the right-side edge.

Furthermore, although the standard lowercase Pi looks like this (π), another variant is also used (ϖ). This glyph variant has been generally referred to as the “pomega”, as it resembles a lowercase Omega that has a macron, a diacritical mark.

Originally, the symbol used for Pomega was actually the cursive form of the lowercase Pi. However, Pomega eventually came to be used for representing different meanings as well, making it an individual symbol altogether.

**The Different Uses and Meanings of the Greek Pi Symbol**

Like the rest of the Greek alphabet letters, the Pi letter is also used to symbolize many things, in different fields. Because the upper and lowercase Pi symbols do not resemble any Latin letters, both are used to denote various concepts.

The most popular use for the Pi symbol is the constant π, called as is (Pi). Also coined as “3.14”, this constant refers to the ratio of the circumference to the diameter of a circle.

Read on to learn more about the other uses for the Pi sign.

**Uses for the Uppercase Pi Symbol**

There are several uses for the uppercase Greek Pi sign. It is used in different fields and industries, from law to science and engineering.

In the field of law, the uppercase Pi is used to represent a plaintiff when writing in legal shorthand. The capital Pi is also used as a symbol that represents the *Codex Petropolitanus*.

The *Codex Petropolitanus *is a Greek uncial codex or manuscript of the Gospels that originated from the 9th century. It is now kept in the National Library of Russia in St. Petersburg.

In science and engineering, the uppercase Pi has several uses. For one, it denotes the product operator in mathematics. This makes the capital Pi notation analogous to the summation symbol, which is represented by the uppercase Sigma.

The capital Pi is also used to symbolize osmotic pressure in chemistry. Another use for the uppercase Pi is to represent the viscous stress tensor in fluid dynamics and continuum mechanics.

**Uses for the Lowercase Pi Symbol**

There are also various uses for the lowercase Pi sign. As mentioned above, one of its most important usages is to represent the ratio between a circle’s diameter and circumference, as used in Euclidean geometry.

The small Pi letter is also used to symbolize the prime-counting function in mathematics. It also denotes the natural projection on a manifold’s tangent bundle.

Meanwhile, in algebraic topology, it symbolizes homotopy groups. The lowercase Pi also symbolizes the unary operation of projection in relational algebra.

In particle physics, the Greek alphabet letter Pi represents the hadron (a composite particle that consists of two or more quarks) known as the pion or pi meson. Meanwhile, in dimensional analysis, it denotes the dimensionless parameters developed through the Buckingham π theorem.

In macroeconomics, the small letter Pi represents inflation rate, while in microeconomics, it represents economic profit.

In chemistry, this letter symbolizes the pi bond, a type of chemical bond wherein the p orbitals overlap each other.

In reinforcement learning, which is an area of machine learning, the lowercase Pi is used to denote “policy”.

**How to Type the Pi Symbol**

Because the upper and lowercase Pi symbols have many uses, you may eventually find the need to type or insert the Pi letter into your documents. Fortunately, the Greek alphabet is widely used in various fields, which is why different methods for typing and inserting Greek alphabet letters are available for use.

**How to Type the Pi Symbol in Word**

There are three ways to add the Pi sign into a Word document. The first method uses an ALT shortcut, while the other two methods use Word’s Insert function.

To use the first method, all you have to do is press and hold the ALT key, then press 2-2-7 on the numeric keypad. Note, however, that this will only work using a full keyboard with a numeric keypad.

For the second method, locate the Insert tab, then click on the arrow beneath “Equation”. Use the arrow keys to scroll through the symbols, choose the Pi from the options, then press Enter.

To do the third method, go to Insert > Symbols > More Symbols to open the Symbol dialog box. On the Subset field, choose Greek and Coptic.

Then, you can either look for the Pi symbol from the options or type “03C0” on the Character Code field. Click Insert, then close the dialog box.

**How to Insert the Pi Symbol in Excel**

When you need to insert the Pi sign into an Excel file, you can also use the Insert tab method. Simply do the same steps as you would insert the symbol into a Word document.

Moreover, you can also try the good ol’ copy-paste method. Simply copy the Pi symbol from any source, then paste it onto your Excel sheet.

**How to Type the Pi Symbol on Mac**

If you’re using a Mac and you need to type Pi, you might be thrilled to know that there are Mac keyboard shortcuts for the letters of the Greek alphabet.

To insert Pi on a Mac, press and hold the Option key, then press P. Release the keys at the same time.