called functions.

A function is a pre-defined formula, and it's used

when a formula

would be too complicated, or just too long.

You can access them from the Formulas tab.

There are hundreds of functions that you can choose from,

and they are organized by category in the function library.

For example, the Financial category contains functions that

deal with things like interest and monthly payments.

The Text category allows you to convert text to

lowercase or uppercase,

replace text, and do other types of text manipulation.

Date & Time includes functions that return the

current date, time, day of the week, and others.

And there are many more functions.

Much of the time, you'll just need to use common

functions such as SUM and AVERAGE, and you can

access these by clicking the AutoSum drop-down arrow.

In this example, I'd like to add all of these cells.

If I tried to create a formula for this, I would

have to add each one individually.

That would get pretty long, and if I had to add

hundreds of cells,

then it would really not be manageable at all.

So I'm just going to add them all by using a

function.

Click on the cell where you want the function to

be, and then

click on the AutoSum drop-down arrow and select Sum.

Now this has inserted the function, and it's also

selected the cells that are being added.

If it selects the wrong cells, then we can always

change that by dragging these corner handles.

But this looks right, so I'll press enter to get

the result.

Let's look at this function in a little bit more

detail.

Just like formulas, functions always start with

the equal sign.

But you might notice that there are no mathematical operators such as addition or

subtraction, like you would normally see in a

formula.

Instead, functions have a specific syntax that

includes the name of the function,

followed by one or more arguments in parentheses.

The arguments tell the function which cells or

numbers to use to calculate the result.

In this example, we actually only have one argument,

even though there are two different cell references.

This is called a range of cells.

A range of cells is indicated by two cell references separated by a colon.

In this case, the range consists of all of the

cells from F6 to F14.

If you want to use more than one argument, you'll

need to separate them with commas.

Let's try a different function now.

In this example, we have a column for the date

that each item was ordered,

and the date that it was received, and I'd like to know how many

business days it took to receive the item after it

was ordered.

First, select the cell where you want the function

to go.

If you know which category your function is in,

you can select it from there, or you can just

search for the function by clicking the Insert Function command.

Just type in a description of what you're looking

for.

I'm looking for a function that can count the

number of days elapsed,

so I'll type "count days" and press Enter.

We've gotten a lot of different results here.

You can click on a function and read a description of it below.

NETWORKDAYS returns the number of workdays between

two dates, and that's what we want.

So I'll click OK.

There will be a field for each argument.

This function has up to three arguments: Start_date, End_date, and Holidays.

When you click in each field, you can see a

description of it below.

If you need more help on a particular function, you can click "Help on this function".

I'll select G6 for the Start date, H6 for the end

date, and the

Holidays argument is optional, so I'll just leave it blank.

You'll be able to see the result here.

Click OK, and the function will be added to the

worksheet.

Just like with formulas, we can drag the fill handle to copy it.

And now we can see how long it took each of these

items to arrive.

If you've never used functions before, the syntax

may seem a little strange at first,

but with some practice you'll start to get the hang of it,

and over time you'll probably find your favorite functions that you'll use over and over again.