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):

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

2. On the Symbol dialog box:

Mar 11, 2013 To access the Equation Editor in PowerPoint 2007 and earlier, choose Insert, Object. In the Insert Object dialog box, scroll down and select Microsoft Equation 3.0. You’ll see a window that looks like this. In PowerPoint 2010 and later, click the Insert tab, then choose Equation in the Symbols group. You’ll see 2 new ribbon tabs.

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.

Provides IT Pros with release notes for Office for Mac releases for Microsoft 365 Apps subscribers.
Mac PowerPoint doesn't have a keyboard shortcut for inserting an equation & doesn't have the facility to create custom shortcuts. However, you can use the macOS method to create one. See the Apple Support Article Create your own shortcuts.

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

Power point for mac insert equation shortcut

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.

Windows

Jump to: Editing text and objects, Working with objects, Presentations, Changing views, Selecting text, Slide shows, Working in tables, Windows and dialog boxes

104 Shortcuts for Microsoft Power Point 2016 (MacOS/ English)

Delete	Delete one character to the left
Function+Delete	Delete one character to the right
⌘+X	Cut selected text or object
⌘+C	Copy selected text or object
⌘+V	Paste cut or copied text or object
⌘+Ctrl+V	Paste special
⌘+Shift+>	Increase the font size
⌘+Shift+<	Decrease the font size
⌘+B	Apply bold formatting
⌘+U	Apply an underline
⌘+I	Apply italic formatting
⌘+E	Center a paragraph
⌘+J	Justify a paragraph
⌘+L	Left align a paragraph
⌘+R	Right align a paragraph
⌘+Y	Redo the last action
⌘+Z	Undo the last action
⌘+T	Open the Format Text dialog box, Font options
⌘+Option+M	Open the Format Text dialog box, Paragraph options
Option+Arrow Left	To Move To the beginning of a word or one word to the left
Option+Arrow Right	To Move One word to the right
⌘+Arrow Right	To Move To the end of a line
⌘+Arrow Left	To Move To the beginning of a line
Option+Arrow Up	To Move To the beginning of a paragraph or up one paragraph
Option+Arrow Down	To Move Down one paragraph
⌘+Arrow Up/Arrow Down	To Move To the start or end of all the text in the object you are editing

Tab	Select the next object
Shift+Tab	Select the previous object
⌘+A	Select all objects and all text
Arrow Keys or ⌘+Arrow Key	Move the selected object in the direction of the arrow
⌘+Option+G	Group the selected objects
⌘+Option+Shift+G	Ungroup the selected objects
⌘+Option+J	Regroup the selected objects
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