## 0.1 What a Spreadsheet is

The spreadsheet is a large rectangular grid of boxes into which you can insert
numbers, messages or commands. This sounds excruciatingly dull, but it has an
important property that makes it incredibly useful as a mathematical tool.

**What's that?**

You can copy the contents of a box into others very easily; and when you do
so the commands in it change to be the same relative to the new box as they
were relative to the old.

**Come again?**

Let us see what can be done with this.

Suppose we insert the number -3 in box A1, and put '=a1+1' in box A2 and also
in box B1. (Don't put the marks '; they are here to enclose what to put
in.)

If we now copy A2 into A3...A1000 (very simple to do when you get the hang of
it) we will get what in column A?

Similarly copying B1 into C1,...,CD1 will produce the same result in row 1.