Write your first formula
20%
A formula starts with an equals sign. That sign is the whole trick: it tells Excel the rest of the cell is an instruction to work something out, not a value to store.
Inside the formula, use cell addresses rather than numbers. =B2+B3 means add whatever is in those two cells. Change B2 later and the answer updates on its own. Type =340+210 instead and you have written a number in a costume. It will still say 550 long after the data has changed.
In B5, write a formula that adds the two amounts in B2 and B3.
B5
| A | B | C | D | E | |
|---|---|---|---|---|---|
| 1 | Invoice | Amount | |||
| 2 | Materials | 340 | |||
| 3 | Labour | 210 | |||
| 4 | |||||
| 5 | Total | ||||
| 6 | |||||
| 7 | |||||
| 8 |
Click a cell and type. Enter commits, Tab moves right, F2 edits in place, Ctrl+Z undoes. Drag the small square at the corner of a cell to fill. Ctrl+Enter checks your answer.