Thursday, March 25, 2010

Writing the Formula in MS Excel

Writing the Formula

Writing Excel formulas is a little different than the way it is done in math class.

Excel formulas starts with the equal sign ( = ) rather than ending with it.

The equal sign always goes in the cell where you want the formula answer to appear.

Rhe equal sign informs Excel that what follows is part of a formula, and not just a name or a number.

Excel formulas look like this:

=3 + 2

rather than:

3 + 2 =

Cell References in Formulas

While the formula in the previous step works, it has one drawback. If you want to change the data being calculated you need to edit or rewrite the formula.

A better way would be to write formulas so that you can change the data without having to change the formulas themselves.

To do this, you need to tell Excel which cell the data is located in. A cell's location in the spreadsheet is referred to as its cell reference.

To find a cell reference, simply look at the column headings to find which column the cell is in, and across to find which row it is in.

The cell reference is a combination of the column letter and row number -- such as A1, B3, or Z345. When writing cell references the column letter always comes first.

So, instead of writing this formula in cell C1:

= 3 + 2

write this instead:

= A1+A2

Note: When you click on a cell containing a formula in Microsoft Excel (see the example above), the formula always appears in the formula bar located above the column letters (circled in red in the example).

Updating Excel Formulas

When you use cell references in Excel formulas, the formulas will automatically update whenever the relevent data in the spreadsheet changes.

For example, if you realize that the data in cell A1 should have been an 8 instead of a 3, you only need to change the contents of cell A1.

Excel updates the answer in cell in cell C1. The formula, itself, doesn't need to change because it was written using cell references.

Changing the data

Click on the cell A1

Type an 8

Press the ENTER key on the keyboard

The answer in cell C1 where the formula is, immediately changes from 5 to 10, but the formula itself is unchanged.

Mathematical Operators

Creating formulas in Microsoft Excel is not difficult. Just combine the cell references of your data with the correct mathematical operator.

The mathematical operators used in Excel formulas are similar to the ones used in math class.

Subtraction - minus sign ( - )

Addition - plus sign ( + )

Division - forward slash ( / )

Multiplication - asterisk (* )

Exponentiation - caret (^ )

Order of Operations

If more than one operator is used in a formula, there is a specific order that Excel will follow to perform these mathematical operations. This order of operations can be changed by adding brackets to the equation. An easy way to remember the order of operations is to use the acronym:

BEDMAS

The Order of Operations is:

Brackets

Exponents

Division

Multiplication

Addition

Subtraction

How the Order of Operations Works

Any operation(s) contained in brackets will be carried out first followed by any exponents.

After that, Excel considers division or multiplication operations to be of equal importance, and carries out these operations in the order they occur left to right in the equation.

The same goes for the next two operations – addition and subtraction. They are considered equal in the order of operations. Which ever one appears first in an equation, either addition or subtraction, is the operation carried out first.

Excel Formulas Tutorial Step 1: Entering the Data

Let's try a step by step example. We will write a simple formula in Excel to add the numbers 3 + 2.

Step 1: Entering the data

It's best if you first enter all of your data into the spreadsheet before you begin creating formulas. This way you will know if there are any layout problems, and it is less likely that you will need to correct your formula later.

For help with this tutorial refer to the image above.

Type a 3 in cell A1 and press the ENTER key on the keyboard.

Type a 2 in cell A2 and press the ENTER key on the keyboard.

Excel Formulas Tutorial Step 2: Add the Equal (=) Sign

When creating formulas in Microsoft Excel, you ALWAYS start by typing the equal sign. You type it in the cell where you want the answer to appear.

For help with this example refer to the image above.

Click on cell C1(outlined in black in the image) with your mouse pointer.

Type the equal sign in cell C1.

Excel Formulas Tutorial Step 3: Add Cell References Using Pointing

After typing the equal sign in step 2, you have two choices for adding cell references to the spreadsheet formula.

You can type them in or,

You can use an Excel feature called Pointing

Pointing allows you to click with your mouse on the cell containing your data to add its cell reference to the formula.

After typing an equal sign in cell E3 in step 2:

Click on cell A1 with the mouse pointer to enter the cell reference into the formula

Type a plus (+) sign

Click on cell A2 with the mouse pointer to enter the cell reference into the formula

Press the ENTER key on the keyboard

The answer 5 should appear in cell C1.

If you have more than one row or column of data that you need to perform calculations on, it is often possible to copy the first formula to other cells.

The easiest way to do this is to copy formulas with the fill handle.

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