Your manager asks, “Why did the total not change after I updated the quantity?” You check the sheet and find that the total was typed manually. This is exactly why formulas matter: Excel should calculate, not you.

What is an Excel formula?

A formula is an instruction that tells Excel to calculate something. Every formula starts with an equals sign =.

For example, =B2*C2 tells Excel to multiply the value in B2 by the value in C2.

Formula rule: Start with =, then use cell references and operators.

Formula example

QuantityUnit PriceFormulaResult
5₹450=B2*C2₹2,250

Common formula operators

  • + Addition
  • - Subtraction
  • * Multiplication
  • / Division
  • ^ Power
=Starts formula
*Multiplication
/Division

Use cell references, not fixed numbers

A formula like =B2*C2 is flexible because it uses values already entered in the sheet. If quantity or price changes, the result updates automatically.

A formula like =5*450 works, but it is hardcoded. It will not reflect changes in your data.

💡
Professional habit: Always build formulas from cell references unless there is a clear reason to use a fixed value.
⚠️
Common mistake: Typing totals manually. This creates errors when source values change.

Copy formulas with Fill Handle

The Fill Handle is the small square at the bottom-right corner of a selected cell. After creating a formula in the first row, drag the Fill Handle down to copy the formula to other rows.

Excel adjusts the cell references automatically. A formula in row 2 becomes row 3, row 4 and so on.

🧪 Practice Lab

Build sales formulas

Download one ZIP file containing the practice workbook, challenge workbook, solution workbook, cheat sheet, quiz and answer key.

📦 Download Lesson 6 ResourcesWorks as a standalone file and after website deployment

Mini practice

  1. Enter Quantity and Unit Price.
  2. Calculate Gross Sales using =Quantity*Unit Price.
  3. Calculate Discount Amount.
  4. Calculate Net Sales.
  5. Change Unit Price and confirm formulas update.

Quick quiz

  1. What sign starts every formula?
  2. Which operator multiplies values?
  3. Why is =B2*C2 better than =5*450?
  4. What is the Fill Handle used for?

Answers: Equals sign; asterisk; it updates with source cells; copying formulas or patterns.

FAQ

The formula may not start with an equals sign, or the cell may be formatted as Text.
You can, but for business reports it is usually better to reference cells so results update automatically.