Level 1 · Line totals with cell references

A spreadsheet cell can hold a value you type, like 12 or Lamp, or a formula: an instruction that starts with = and computes a value from other cells. Formulas are why analysts use spreadsheets at all. Change a quantity, and every total that depends on it updates by itself.

Cell references

Every cell has an address: its column letter and its row number. In this sheet the first order line is in row 2, so its quantity sits in C2 and its unit price in D2. A formula that multiplies them is:

=C2*D2

Type it in F2 and press Enter. The cell shows the result (9 × 31.99 = 287.91), and the formula bar above the grid still shows =C2*D2. That difference matters: the cell holds the instruction, not the number. If someone corrects the quantity in C2, F2 changes too.

The arithmetic operators are the ones you know: + add, - subtract, * multiply, / divide, and ^ for powers.

Percentages and brackets

discount_pct stores a discount as a whole number: 10 means 10% off. To get the price the customer actually pays, keep the remaining share: 1 - 10/100, which is 0.9. So the full line total is:

=C2*D2*(1-E2/100)

Excel follows the usual order of operations: brackets first, then ^, then * and /, then + and -. Without the brackets, =C2*D2*1-E2/100 computes C2*D2*1 first and then subtracts a tiny 0.1, which is almost no discount at all. When a formula mixes + or - with * or /, add brackets so the intent is visible.

Filling a formula down

You need the same calculation on twelve rows. Writing twelve formulas by hand is slow and error prone. Instead, write it once in F2, then fill it down:

• select F2:F13 (click F2, then Shift+click F13) and press Ctrl+D (Cmd+D on a Mac), or
• drag the small square on the corner of F2 down to row 13, or
• on a phone, select the cell and tap Fill down.

Excel copies the formula and moves every reference with it: F3 gets =C3*D3*(1-E3/100), F4 gets row 4, and so on. These are relative references, and they are what makes one formula work for a whole column. Level 3 shows what to do when a reference must not move.

Common mistakes

• Typing the result instead of a formula. 287.91 is right today and wrong tomorrow. The checker asks for formulas for exactly this reason.
• Forgetting the =. Without it, Excel stores the text C2*D2 and shows it as a label.
• Treating the percentage as a fraction. =C2*D2*(1-E2) subtracts 10, not 10%, and gives a negative total.
• Spaces in the wrong place. = C2 * D2 works, but =C 2 does not: an address is one word.