Lesson 2 of 5 · about 25 minutes

Your first spreadsheet: the stock sheet

🏠The everyday picture

A stock register has columns ruled across the top (item, opening stock, sold, left) and one row for each item. A spreadsheet is that register, already ruled. The difference is that the "left" column can do its own subtraction, every time, without a mistake.

📘What it really is

A spreadsheet is a grid:

Columns go down and are named by letters: A, B, C...
Rows go across and are numbered: 1, 2, 3...
Each box is a cell, named by its column and row. B2 is column B, row 2.

A cell holds either something you type (text or a number) or a formula. A formula always starts with = and works something out. =B2-C2 means "take what's in C2 away from what's in B2". When B2 or C2 changes, the answer changes too.

📝A worked example

Gupta General Store wants to know what's left on the shelf. Type this, starting in cell A1:

	A	B	C	D
1	Item	Opening stock	Sold	Left
2	Rice 5 kg	20	7
3	Atta 10 kg	15	12
4	Sugar 1 kg	40	18
5	Tea 250 g	30	26

Now click cell D2 and type =B2-C2, then press Enter. It shows 13.

You don't need to type the formula three more times. Click D2 again, then drag the small square at its bottom-right corner (the fill handle) down to D5. The sheet copies the formula and changes the row each time: D3 gets =B3-C3, D4 gets =B4-C4. You should see 13, 3, 22 and 4.

🖱️Try it

Build the sheet above in your own stock-sheet file, then:

Change Sold for Atta from 12 to 10. Watch "Left" change to 5 by itself.
Add a sixth item in row 6 (for example "Salt 1 kg", 25, 9) and fill the formula down one more row.
Make row 1 bold, so the headings stand out.

⚠️Common mistakes

Forgetting the =. If you type B2-C2 without it, the cell just shows the letters. Start every formula with =.
Typing the answer instead of a formula. If you type 13 into D2, it stays 13 even when the stock changes. Click a cell and look at the formula bar above the grid: it shows whether a cell holds a typed number or a formula.
Units inside numbers. Type 20, not 20 bags. "20 bags" is text, and text can't be used in a sum. Put the unit in the heading instead: "Opening stock (bags)".

✅Quick check

Cell D4 shows 22. How can you tell whether someone typed 22 or a formula worked it out?

Show the answer

Click D4 and look in the formula bar above the grid. If it shows =B4-C4, it's a formula; if it shows just 22, someone typed it.

You fill =B2-C2 from D2 down to D5. What formula ends up in D5?