Spreadsheet sums and formulas
A spreadsheet is a big grid. Columns have letters and rows have numbers, so every cell has a name such as B2. You can add selected cells with a sum button. Or you can write a formula. A formula always starts with an equals sign. Then you use the cell names and these signs: plus (+) to add, minus (−) to subtract, a star (*) to multiply and a slash (/) to divide. For example, a formula that adds three cells in column B will show the total, and when you change a number in one of the cells, the total changes by itself. This is the great strength of a spreadsheet. You can practise on paper: draw a grid, write the cell names and calculate by hand.
| A | B | C | |
|---|---|---|---|
| 1 | Day | Bottles | Cans |
| 2 | Mon | 4 | 3 |
| 3 | Tue | 6 | 2 |
| 4 | Wed | 5 | 4 |
| 5 | Total | 15 | 9 |
| Formula | What it does | Answer |
|---|---|---|
| =B3-C3 | subtract | 4 |
| =B2*2 | multiply by 2 | 8 |
| =B3/2 | divide by 2 | 3 |
Paper spreadsheet. Draw a grid with columns A, B, C and rows 1 to 4. Write headings in row 1 (for example ‘Day’, ‘Boys’, ‘Girls’) and invent numbers in rows 2 and 3. In row 4 write the totals. Under the grid write the formulas you would type in B4 and C4 and a formula that finds the difference between B2 and C2. Calculate each answer by hand. Then change one number in row 2 and recalculate. Explain to a partner why a spreadsheet saves time.