Microsoft Excel 
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UNDERSTANDING FUNCTIONS 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Imagine having to create a formula that 
calculated the monthly payments on a loan, or 
the average of over 100 cells – these would 
require complex or long formulas that would be 
time consuming to develop. This is the role of 
hundreds of arithmetic functions that have been 
pre-programmed in Excel for you. 
Functions Overview 
Functions are simply pre-programmed formulas already provided for you in Excel which can perform 
calculations covering a wide range of categories including statistics, date and time arithmetic, financial 
calculations, lists, engineering, and more. 
Just like normal formulas that you create, functions must start with an equal sign. The equal sign is 
then followed by the name of the function (usually a descriptive name which indicates the purpose of 
the function). Most functions also require additional information known as arguments which are 
supplied to the function in brackets after the function name. Functions are therefore written as follows: 
=name(arguments) 
The arguments are quite often cell or range references that contain values that can be used in the 
function. For example, the commonest function is the SUM function which, as its name suggests, is 
used to sum or add values together. If you wanted to add all of the values in the cells from B10 to D15 
you would write this function as: 
=SUM(B10:D15) 
As you can see this is much simpler than writing your own referential formula which would look like:  
=B10+B11+B12+B13+B14+B15+D10+D11+D12+D13+D14+D15 
Imagine writing and proofing a formula where you had to add 200 cells!  
Typing Functions 
If you are familiar with the function that you need you can type it into a cell exactly the same way you 
type any other formula. If you are not sure if Excel has a function or you can’t quite remember how it is 
written you can use the Insert Function
 tool  on the Formula Bar to assist you. When you click on 
this tool the Insert Function dialog box will be presented to you which lists the most recently used or 
common functions and also allows you to search for other functions that you might need.  
 
The Insert Function dialog box will also type the function out for you and then provide you with a 
further dialog box to guide you through the process of specifying the arguments that the function 
needs to perform its calculation.