# Introduction to Spreadsheets

A Spreadsheet is a program that allows you to enter and manipulate numbers: they are essentially a large multi-dimensional matrix which allows you to add numbers, text and formulae. Data entered can then be sorted, manipulated and graphed as desired

Spreadsheets are not very exciting until you start using formulae: these tell the application to calculate the value of a cell according to a rule specified by you ..

When you open a spreadsheet, it initially looks like a piece of digital graph (squared) paper. However, you will notice that from left to right along the top are a series of column headings (e.g. A-Z) and down the left hand side are the row headings (e.g. 1-100). Each individual cell in the main window is referenced by a unique ID formed from the column name followed by the row number. For example, a cell in column A, row 10 would be referenced as cell A10 whereas one in column BJ, row 100 would be BJ100. Data can be placed in each of these cells - and can this can be of several basic types:

- Text (e.g. headings, descriptions)
- Numerical
- Date
- Function (-such as +-/*, sum, count, etc)
- Formula

The power of spreadsheets comes from the latter: a *formula* is an algebraic expression which can include any of the other data types, plus a *reference to another cell in the spreadsheet*. So for example, if you entered "sum($E4:$E9)", the spreadsheet would place the result of the sum of all the values in columns E4 to E9 in that cell. This means that if you change one of the values in E4-E9, then the value in this cell will also change. Here are a few basic formulae examples:

**$A1+$B5** (-substitute the value of cell A1 added to that of cell B5)**sum($A5:$A10)** (-substitute the values of cells A5,A6,A7,A8,A9,A10 added together)**($B5*3)+$C10** (-substitute three times the value in B5 plus the value in cell C10)

The classic use for spreadsheets is so-called *What-if* scenarios. When you enter data using a mix of numbers and formulae, you can play with the numbers columns to see what effect changes have on the calculated columns. For example, you could type in your share portfolio and change one cell to see the effect that a change in different share prices (-or exchange rates) have on it's value.

Suppose a call centre wants to find out where it was spending the most amount of it's staff time: it could pull the data on closed calls from it's call logging database into a spreadsheet and use it to:

- Assign a category to each call
- Add up the time the time spent on calls in each category
- Sort the categories in order of time spent
- Create a chart showing the percentage of time spent per category for presentation to management

In the home environment, some typical uses of a spreadsheet would be:

- Tracking household expenses
- Analysing utility (gas/electric/water) usage
- Financial Projections (savings, investments, bank account, etc)
- Raw Data that requires processing (-i.e. creating pie charts, bar graphs, etc)