CS130/230 Lecture 1

Introduction to Excel

Monday, January 5, 2004

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What is Microsoft Excel?

Basically, Excel is a spreadsheet (SS) program that allows the user the ability to organize data, do basic/advanced calculations, do what-if analysis, graph data, create professional reports, publish info to the Web, access real-time data from the Web. We will do all of these things through the four major parts of the Excel application:

· Worksheets: where we will enter, calculate, manipulate and analyze data.

· Charts: to represent our data pictorially.

· Databases: to manage the data. We can search, sort and select.

· Web Support: to save data in HTML format.

Let's begin by going to the Start menu and launching the Excel application. Your screen should look something like the following (only much larger):

As with most applications, Excel contains both a menu bar and a toolbar. Depending on the version of Excel that you are using, the menu bar and toolbar options might look a little different. Also, even though the Mac and Windows files are pretty much compatible, there are differences between the UIs (User Interfaces) in the Mac and the Windows environments.

Workbook

When you first start Excel, it opens up with a new workbook called Book1. This workbook contains three worksheets by default but you can add many more. This is similar to having a notebook with many sheets of paper.

Worksheet

Worksheets consist of a grid or rows and columns. Each worksheet consists of cells, which are the basic building blocks of every worksheet.

A cell is referred to by it’s unique address or cell reference.

Question: What is an active cell and how do we know which cell is currently active?

Cells

You can enter various types of information into cells in various ways. The simplest type of information is text, which you just enter by selecting the cell and typing the text.

You can also enter numbers (or values) by typing in any of the number characters and acceptable symbols. Valid number symbols are = - ( ) , / . $ % E e. Do not put any spaces in a number or Excel will interpret it as text.

Formulas

Formulas are a different type of data that you can enter into the cell. A formula begins with an equal sign followed by a well-formed expression. If the equal sign is missing, chances are that the cell data will be interpreted as text unless a simple number is typed in.

Question: If we place the formula =3+9/3-1 into cell A1, what value gets displayed? Why?

Question: Excel contains several binary arithmetic operators. What is a binary operator and what are the five most common binary operators?

Question: What is operator precedence and how does it apply to the above binary operators listed in the previous question?

Question: What is the value of each of the following formulas?

· =2+4/2

· =4/0

· =0/4

· =2*3+5/2

· =2*/3

· =2*-1

Question: Consider the formula =2+3+6. When we talk about the associativity operator, what do we mean and how does it apply to this formula?

Cell References

Not only can numbers be placed in cell formulas, cell references can be used in cell formulas.

Question: What does the following formula mean? =A1+2

Problem: Place the values 10, -3 and 22 in the cells A1, A2, and A3 respectively. In cell, A4, write the formula to find the average of the values in cells A1 to A3. Then change the value in cell A2 and the value in cell A4 should be modified as soon as you hit return.

Cell references in formulas can be relative or absolute.

· Relative references: refer to cell references in formulas in relation to the cell that contains the formula. This is what we’ve been using so far.

· Absolute references: refer to cells in their absolute or fixed position.

Filling

Typically, when creating SS, you want to get some pattern going so that you can do some kind of fill either down or right. When filling, Excel adjusts the cell references in formulas based on whether they are relative or absolute.

Let’s go back to our worksheet. Right now A4 calculates the sum of the values in A1, A2 and A3. What if we want B4 to calculate the sum of the values in B1, B2 and B3, and C4 to calculate the sum of the values in C1, C2 and C3, and so on till column E. Enter the values that we want to sum in B1, B2, B3, C1, C2, etc.

Now, since the formula in A4 uses relative cell references, you can just select that cell, and drag from the bottom right hand corner to the right. This is called filling.

What you’ll notice is that B4 now contains the formula =B1+B2+B3.

Question: How can you view the formula in a cell?

An alternative to dragging is to copy A4 and paste it in C4. This is also filling.

Problem

You are just starting college and you have calculated your expenses for your freshmen year as described below. You would now like to project what your expenses will be for each category for the next three years assuming that there will be a 6% increase in all expenses.

Category Expenses

Clothes 540

Entertainment 725

Miscellaneous 355

Room & Board 3480

Tuition & Books 5150

How would you proceed?

Assume that you now want to find out what your total expenses for each year will be. What would you need to add?

Now suppose that you would like to see what your expenses will be if the increase was 7% or 8%. What changes would we have to make to the spreadsheet (SS)?

Formatting

Excel provides some advanced formatting capabilities to make your spreadsheet look more professional. The one that you should start using now is the cell formatting option. You get to this option by selecting the cell or cells you want to format and going through the format menu and clicking on cell then selecting the number tab. From here you can choose the type of number in your cell. The ones you are interested in now are the currency and percentage options.

From now on, any numbers that you have in your worksheet should be formatted appropriately.

Absolute Cell Reference

What is the difference between a relative and absolute reference again?

Absolute references are specified using a $, so for example, a cell reference of $A$1 references cell A1 and any subsequent copy of the cell reference into another cell still produces $A$1.

It is also possible to make just the row or column reference absolute as follows: $A1 or A$1.

Question: How do these two references differ from $A$1?

Problem

Modify the college expenses SS so that the user just has to change the yearly percent increase and the rest of the SS is updated with the proper values.

Error messages

Excel has several error messages that you should be aware of and the main ones are:

· # - A ##### error value occurs when the cell contains a number, date, or time that is wider than the cell or when the cell contains a date and/or time formula that produces a negative result.

· #DIV/0! - The #DIV/0! error value occurs when a formula divides by 0 (zero).

· #na - No information is available for the calculation you want to perform.

· #NAME? - The #NAME? error value occurs when Microsoft Excel doesn't recognize text in a formula.

· #NULL! - The #NULL! error value occurs when you specify an intersection of two areas that do not intersect.

· #REF! - The #REF! error value occurs when a cell reference is not valid.

· #VALUE! - The #VALUE! error value occurs when the wrong type of argument or operand is used, or if the Formula AutoCorrect feature cannot correct the formula.

Problem

A meteorology class found the average weekly temperature for each week of each month for one year. The data follows. You are to find each of the following using a SS:

The average monthly temperature for each month.
The highest and lowest monthly averages using two functions we have not discussed yet: maximum and minimum. See if you can use the help feature to figure this out.

Month Week1 Week2 Week3 Week4

jan 33 36 29 31

feb 37 32 39 38

mar 43 47 38 45

apr 49 51 53 50

may 52 55 54 58

jun 56 62 61 60

jul 65 69 73 70

aug 72 74 68 69

sep 67 66 64 60

oct 63 65 60 59

nov 46 42 45 40

dec 38 35 36 35