So, there are several different ways to do it:

I. The traditional method is to use the ribbonSymbol button (a popular approach for social science, which does not need much mathin the text):

The standard deviation formula is denoted by the greek lower case sigma symbol in the case of the population and the latin letter s for the sample. To insert the lambda, sigma and theta letters in a Word document, you have different ways. Using the Symbol font: This method is very useful when you need to insert symbols rarely and it works only for Latin or Greek letters. Anytime, when you type the text in the Word document, you can switch to the Symbol font and use the corresponding Latin letters to enter Greek letters. To enter an ALT code, insure Num Lock is on, press the ALT key, and type on the numeric keypad. The letters are in the following order: Alpha, Beta, Gamma, Delta, Epsilon, Zeta, Eta, Theta, Iota, Kappa, Lambda, Mu, Nu, Xi, Omicron, Pi, Rho, Sigma, Tau, Upsilon, Phi, Chi, Psi, and Omega. ○ This tutorial contains affiliate links.

1. On the Insert tab, in the Symbols group, click theSymbol button:

2. On the Symbol dialog box:

• In the Font dropdown list, choose the Symbol font:
• Choose the symbol you want to add into your slide:
• Click Insert and then click Cancel.

II. Using Alt+code shortcuts: this way is the perfect oneif you remember all codes:

In the slide, hold Alt and then enter the Unicode code of the symbol.

For example, for the Greek lambda letter, you need to hold Alt and then enter 108.

Note: you can see all the codes in the Symbol dialog box:

III. Using embedded equitation: this way is perfectif you don't need to care about the format and compatibility with previous versions of MicrosoftOffice (a popular approach for physical science and mathematics, which do need a lot of math inthe text):

1. In the slide where you want to insert the symbol, clickAlt+= to insert the equitation block:

2. In the equitation block without any additional efforts, you canenter any letter that you need just by typing +Name of the letter:

alpha	kappa	varrho
beta	lambda	sigma
chi	mu	varsigma
delta	nu	tau
epsilon	o	upsilon
varepsilon	pi	omega
phi	varpi	xi
varphi	theta	psi
gamma	vartheta	zeta
eta	iota	rho

To insert a capital letter of the Greek alphabet, simply enter +Name of the letterstarting with a capital letter:

Delta	Phi	Gamma
Lambda	Mu	Pi
Theta	Sigma	Upsilon
Omega	Hi	Psi

How to insert other symbols and templates in an equation, see Howto insert the mathematical and other symbols into the PowerPoint slide.

3. After entering the letter name, click the space,the sequence will be replaced by the corresponding symbol.

4. Click Alt+= again to exit from the equitation.

Now you can continue entering your text.

Note: In the Autocorrect Options, you will find all ofName of the symbol sequences that you can use. To open the options dialog,do the following:

1. On the File menu, click the Options button:

2. In the PowerPoint Options dialog box, on theProofing tab, click the AutoCorrect Options... button:

3. In the AutoCorrect dialog box, choose the MathAutoCorrect tab:

The Math AutoCorrect tab shows all Names of symbols that can be used forinserting the Greek letters and other mathematical symbols.

Note: AutoCorrect options work through all Microsoft Office products on this PC, laptop, etc. Ifyou change some of them in PowerPoint, you will see all changes also in Word, Outlook, and Excel.

See also this tip in French:Comment insérer des symboles grecs très rapidement.

To insert the lambda, sigma and theta lettersin a Word document, you have different ways:

I. Using the Symbol font:

This method is very useful when you need to insert symbols rarely andit works only for Latin or Greek letters.

Anytime, when you type the text in the Word document, you can switch to the Symbolfont and use the corresponding Latin letters to enter Greek letters:

1. Click Ctrl+Shift+Q to switch your currentfont to the Symbol font.

2. Use symbols like normal font (e.g. in Symbolfont keyboard button 'a' equals Greek letter 'α', keyboard button 'b'equals Greece letter 'β', ..., 'l' ->'λ', ..., 'w' -> 'ω', etc.):

Sigma Symbol In Word 2007

Note: This method works for inserting only one letter. Thus, if you want toinsert several symbols, you need to repeat these steps for each insertion.

After entering one letter using the Symbol font, the next character is entered usingthe previous font.

If you click Ctrl+Shift+Q twice, Word does not switch to the previous font, and theSymbol font doesn't stop to work after the first entered symbol. Thus, you will needto change the current font and style later.

II. Using the Equation:

This way is perfect if you don't need to care about the format and compatibilitywith previous versions of Microsoft Office (a recommended approach for physicalscience and mathematics, which require a lot of math in the text with consistentfonts for all equations and symbols):

1. In the paragraph where you want to insert thesymbol, click Alt+= to insert the equitation block:

2. In the equitation block without any additionalefforts, you can enter any letter that you need just by typing+Name of the letter:

Note: You can create a shorter name, see the point III.2.

III. Using auto-replace:

When you work with many documents and often need to paste one specialsymbol, you may not want to insert an equation each time. Microsoft Word offers ahelpful feature named AutoCorrect. The AutoCorrect options in MicrosoftWord propose two different ways to quickly add any special character, such as alambda, sigma or theta letter from the Greek alphabet, or evenlarge pieces of text:

• Using the Math AutoCorrect options,
• Using the Replace text as you type function of the AutoCorrectoptions.

III.1. Using AutoCorrect for Math:

Using this method, you can benefit the Math AutoCorrect options without inserting anequation. To turn on or turn off the AutoCorrect of the Math symbols, do thefollowing:

1. On the File tab, click Options:

2. In the Word Options dialog box, on theProofing tab, click the AutoCorrect Options... button:

3. In the AutoCorrect dialog box, on theMath AutoCorrect tab, select the Use Math AutoCorrect rules outside of the math regionsoption:

After clicking OK, you can use any of the listed Names of symbols andMicrosoft Word will replace them to the appropriate symbols:

Note: If you don't need the last replacement, click Ctrl+Z to cancel it.

III.2. Using Replace text:

Using this method, you can come up with some sequence to use for replacing it to theLatin or Greek letter. For example, to replace some Greek letter with not short names,it is possible to use:

To define the new, short names to some Greek letters, do the following:

1. Insert the symbol for which you want to definethe short name, using the Symbol font and select it.

2. On the File tab, click Options.

3. In the Word Options dialog box, on theProofing tab, click the AutoCorrect Options... button.

4. In the AutoCorrect dialog box, on theAutoCorrect tab:

• Ensure that the Replace text as you type option is selected,
• The selected symbol has been inserted in the With field. If you use theFormatted text, select this radio button:
• In the Replace field, type the sequence that should be replaced to thesymbol,
• If such sequence doesn't used yet, click Add.

IV. Using a shortcut key:

Microsoft Word provides a way to define the shortcut key for the most often usedfunctions. Thus, you can assign a shortcut for inserting the lambda,sigma or theta letter:

1. On the Insert tab, in the Symbols group,click the Symbol button:

Note: If you use the character very often, you will find it in the Symboldropdown list:

2. Click More Symbols....

3. On the Symbol dialog box:

• To insert the lambda, sigma or thetafrom the current font (if exist), from theSubset dropdown list, select the Greek and Coptic:
• To insert the lambda, sigma or thetafrom the Symbol font, from theFont dropdown list, choose the Symbol font:

4. Choose the symbol and click the Shortcut Key...button to open the Customize Keyboard dialog box:

How To Type Sigma Symbol In Word Document

5. In the Press new shortcut key field, type the keycombination that you want to use for the symbol or character (e.g., for symbol λused Alt+L) and click Assign.

Sigma Symbol In Word 2013

Note: Be careful, you can reassign the assigned already shortcuts in Word. Besure, that after Current assign to: there are no active Word functions. In any case,you can reassign any existing function in Word to a different key.

Sigma Symbol In Word 365

See also this tip in French:Comment insérer lambda, sigma, thêta et autres symboles grecs dans Word.