Calculate the perimeter of a square with side 9 cm.

**The reasoning** A square has **four equal sides**. The perimeter means the total distance around the shape – like fencing around a compound. So: Perimeter = side + side + side + side = 4 × side Given: side = 9 cm Perimeter = 4 × 9 = **36 cm** That's it! You're adding all four sides: 9 + 9 + 9 + 9 = 36 cm. **Why the wrong options tempt you** - **A) 18 cm** – This is 2 × 9. You only counted *two* sides, maybe thinking of diameter or confusing square with something else. - **B) 27 cm** – This is 3 × 9. You forgot one side! Easy mistake under exam pressure. - **D) 81 cm** – This is 9 × 9 = 9². You calculated the **area** instead of perimeter. Common mix-up! **Quick takeaway** Perimeter of a square = **4 × side** (distance *around*), while Area = side² (space *inside*) – don't let exam stress make you confuse the two!