Excel 2003:

.xls = Workbook

.xla = VBA Add-in

.xlb = Toolbar (where custom toolbar settings are stored)

.xlc = Chart

.xld = Dialog (from older versions of Excel)

.xlk = Archive (Excel spreadsheet backup)

.xll = DLL Add-in

.xlm = Macro

.xlt = Template

.xlv = VBA Module

.xlw = Workspace (collection of multiple Workbooks)

Excel 2007:

.xlsx = Workbook (XML format)

.xlsm = Macro-enabled Workbook

.xlsb = Excel Binary Workbook (instead of XML format)

.xltm = Macre-enabled Template

.xlam = Add-in (XML format)

http://wiki.answers.com/What_is_the_file_extension_that_indicates_an_excel_file#ixzz16E1eq6Mr

There are many uses for Excel. If you have novel ways to use Excel, please add your ideas here or on the discussion page.

Here are some ideas:

• Set up a favorite friend list and enter the number of SMS messages you send them each month. The person at the end of the year that received the most messages is your favorite texting friend.
• Plan a vacation budget. Decide how much money you will spend for your vacation and set up a budget for each item. Take the budget with you and keep track of actual expenses. When you get back, enter actual expenses and compare with budgeted expenses. Use this information to help plan your next vacation.
• Design a form. You can change the column width to 2 characters to create a grid system to allow you to layout a form. Join several cells together to create each form area.
• Create a mailing list and use this list to merge with a letter you make in Word. You can send out annual letters to all of your friends keep them up to date on what is happening with you. In the mailing list, include personal information about the person. That way, you can personalize each letter in a mass mailing to your friends.
• Set up a work schedule and calculate how many hours each worker is required to work. You can break down the totals by week, month, year, or any other time period you choose.
• Track income and expenses to see what your profits are at the end of each week, month, quarter, and year.
• You can use Excel as an advanced calculator to calculate almost any kind of math of financial problem. Excel can calculate the square root of any number a quickly as you can press the enter key.
• Use it to track the birds or other animals you see in your back yard. You can set up columns for type of animal, time of day, day of week, how long they stayed, what they did, etc.
• Collect and track weather data, then create charts to view and evaluate the data over time. You can see what day was the hottest last year, how many days rained, what day received the most snow, etc. The amount of data you collect is limited only by your imagination.
• Evaluate different purchase options. If you want to purchase a new car, you can record as much data as you can find about each type of car you would like to consider, then make charts to view and help analyze data. You can assign a point value to each car feature then total up the points to see which car gets the most points.
• You can keep track of various baseball statistics to compare your stats with what the sports casters are talking about. You can create your own unique best-of categories, like which team got the most strikes on days that were cloudy.

  Track daily meals to find out how many calories you consume each day, week, month, year, etc. You can sort the data to see if there are any days of the week where you consume more or less calories compared to other days.

• If you have health issues, you can track your blood sugar, temperature, blood pressure, weight, etc. to see if you are meeting or exceeding expected results over time. You can create a chart that shows you almost any way you would like to view the results.
• As a classroom project, you can give each student a bag of M&Ms, Skittles, or some other snack that uses different colors. Have the students record how many of each color is in the bag. Then the students can create charts to view and evaluate the results of their study.
• Create a simple inventory sheet to determine how many items you have in stock, the total value of each item, the total value of all items, color-coded totals to show which items should be reordered, etc.
• Make a decision matrix. Along the side of the spreadsheet, list all of the items you would like to evaluate. Across the top list all the criteria that you want to consider in your decision. For example, you want to decide where to go on a vacation. You list all the places you might want to consider along the left side. Across the top you list things like, cost, distance, things to do, etc. Assign relative values to each criteria for every option (e.g. 3 = Best, 2 = OK, 1 = Maybe, 0 = Not a chance). Create a formula to add all the values and see which option gets the most points.

It can be used to manipulate dates and text. It has some graphical capabilities, as you can craw things in it. You can use it to make flowcharts and structured diagrams. It can be good for creating structured forms for printing out. It can be used for databasing. It has a lot of other uses that you can come up with once you start using it.

See related links for more great ideas about how to use Excel and to download some free helpful Excel templates.

• Track a budget (find out home much money you have coming in and how much you have going out).
• If you have a large collection of something, you can list the the items and their price, then you can add a total to each list. Every time you update any of the values, the total value automatically updates. Additionally, you can have several worksheets, one for each of your collectable items, and a totals worksheet that provides an overview of your entire collection. Each of the individual worksheets can be linked to the overview, so you can see all the important information about your collection on a single page.
• Make a decision matrix to help you choose between several options (courses of action). You can list your options across the top and the criteria you would like to evaluate along the side. In the cell where each criteria matches an otion, you can enter a number to indicate your preference. Add the columns listing your preferences, and the one with the highest number (or lowest number, depending on the measurement scale you choose) meets most of the criteria you have selected. A large number on a decision matrix is not the only reason you should select a course of action, but it is a tool to help point you in the desired direction.

See related questions for ways to use Excel.
Microsoft Excel is a spreadsheet program. A Spreadsheet is a computer application used for numerical analysis and manipulation. A Spreadsheet is split into Columns and Rows based on an accountant's worksheet.

Columns are referenced by letters.

Rows are referenced by numbers.

Where a Column and a Row intersect a Cell is formed.

A Cell is referenced by its Column letter and Row Number (e.g. A12 = Column A; Row 12).

A Range or Block is a rectangular group of cells referenced by the top left and bottom right cells.

A Spreadsheet has thousands of columns and thousands of rows and therefore millions of cells.

One of the most powerful features of a spreadsheet is the ability to use formulas for calculations. Formulas should always be used in preference to manually working out results of calculations. All formulas in Excel begin with the = sign.

Functions are pre-written formulas that come supplied with the Spreadsheet to enable the user to carry out specialised or common tasks. There are functions to do a wide range of tasks. The functions are usually classified under various headings, including Mathematical, Logical, Special, Text, Date/Time, Financial, Statistical and Database Functions. You can do things related to all of these areas, and almost anything that is related to numbers and calculations.

You can make simple spreadsheets, make databases, use it for accountancy, for stock control and a whole range of other things. Businesses use them for doing planning and evaluation in relation to things like their sales and how their business has been doing and how they expect it to do. You can also use it for creating graphs or diagrams. You can use it for creating structured forms. In short, a spreadsheet is one of the most useful of all applications, enabling you to do a wide range of things.
A spreadsheet is a collection of rows and columns, which are used to organize data in such a way that the arithmetic operation can be carried out on whole rows of columns extremely quickly.

• to use spreadsheets as modeling tools
• plan, design and create a database

• The benefits of a spread sheet include the fact that you can make formulas and work out complex sums easily.

Whether you just want to add up rows/columns of numbers or do advanced calculations.

eg: if column 1 total is subtracted from column 6 total, what is the answer? or

if this particular information is a percentage of that information, what percentage is the remaining information in relation to column X.

Many and varied calculations can be done in relation to any information.
You can create spreadsheets or tables.

For example when you need to do your accounting, tax returns or so.
Microsoft Excel is used to make spreadsheets, do calculations, make graphs, and make tables.
Exel is a spreadsheet program that enables you to enter formulas and data into the cells in order to organize information.
you can make charts,diagrams,various mathematical calculations,convert money,measurements,text document connect to database,insert content from web pages and many,many more
1) Perform repetative and complex mathematics

2) Connect to a database to get snapshots of data

3) Create dynamic graphs on data quickly and easily

4) Sort and filter large volumes of information quickly

5) Validate user input; allowing them to use dropdown boxes and enforcing rules on the data

Enter one set of numbers in a column and another set of numbers in a row at the top of that column, so that the numbers you want to multiply intersect at a column and row.

EXAMPLE:

In A2 enter 2.

In B1 enter 3.

In B2 enter =A2*B1 (observe the answer 6)

TIP: If you want to be able to enter the formula only in the first intersecting cell of the row, then copy the formula to all the rest of the cells in the row, use the formula =$A$2*B1. That will make A2 and absolute reference that will not change as you copy the formula to other cells in the row, but will automatically update B1 to C1, D1, etc.

To convert from decimal to octal, use the function DEC2OCT.

EXAMPLE: =DEC2OCT(58, 3) Converts decimal 58 to octal (072).