Google Sheets is a powerful spreadsheet program that performs complex computations on the data you enter into each cell. The application uses formulas and functions to do these tasks so you don't have to. A formula is an expression that you input to tell Google Sheets how to calculate the value of a cell, and a function is a predefined formula that Google Sheets has created for you.
The instructions in this article apply to Google Sheets.
Why Use a Function?
The difference between a formula and a function is that you create formulas to perform a computation and functions are prebuilt formulas found in Google Sheets. Functions save time and reduce the chance of errors.
For example, to add a row of numbers using a formula, the following is entered into a cell in Google Sheets:
=A1+B1+C1+D1+E1+F1
To add the same row of numbers using a function, the following is entered:
=SUM(A1:F1)
Using a function is efficient when working with a large number of items or for more complex computations.
Google Sheets Function Syntax
Each function has a syntax, which is the specific order in which the elements for the function to perform the desired calculation are entered.
Every function begins with the function name, followed by the arguments, which are separated by commas or a colon and enclosed in parentheses. The basic construction of a function is:
Function_Name(argument1,argument2)
Here's an example:
SUM(A1,B1)
How to Use Google Sheets Functions
The fastest and easiest way to use a function is from the Functions menu.

Select the cell where you want to display the result of the calculation.

On the toolbar, select Functions, then choose a function. There are five basic functions, plus submenus that contain every possible function. The five basic functions are:
 SUM: Adds the values in a range of cells
 AVERAGE: Calculates the average of the values in a range of cells.
 COUNT: Provides the number of values in a range of cells.
 MAX: Provides the highest value in a range of cells.
 MIN: Provides the lowest value in a range of cells.

Choose the cells to include in the range.
To choose individual cells, rather than consecutive cells, press and hold Ctrl and make your selections. To choose a continuous range of cells, press and hold Shift and select the first and last cells in the range.

Press Enter.

The result appears in the selected cell.
How to Use Complex Functions in Google Sheets
Google Sheets includes dozens of functions that perform a wide variety of tasks. For example, to calculate the number of days or the number of working days (Monday through Friday) between two dates.
To find the right function, reference the complete list of Google Sheets functions. To narrow down the options, enter a search term in the Filter field and press Enter to see your choices. For example, to find the function to calculate the number of days, enter days as the search term. Two possible results are the DAYS and NETWORKDAYS functions.
Alternatively, go to the Google Sheets toolbar, select Functions, then choose a submenu at the bottom of the list.
Some functions require data to be input in a particular way. Here's how to do it, using the NETWORKDAYS function as an example.

Select the cell where you want to show the number of working days between two dates.

Enter =NETWORKDAYS.
To use this function, you can start with a blank spreadsheet.

Two options are displayed: NETWORKDAYS and NETWORKDAYS.INTL. Select NETWORKDAYS.

The correct format used to enter the function is displayed. Review it, then select X to exit.

Enter the start and end dates of the date range using the same format as the formula. Pay close attention to punctuation placement.

Press Enter.

The number of workdays appears in the selected cell.
How to Use Functions with Text in Google Sheets
Google Sheets functions can be helpful with text as well. For example, the GOOGLETRANSLATE function translates selected text from a source language to another specified language.
Here's how to do it, using the Spanish word hola as an example:

Select the cell where you want the translated text to appear.

Enter =GOOGLETRANSLATE("HOLA")

Press Enter.

The translation appears in the selected cell.