1. **State the problem:** We need to determine which of the given areas is the largest. The areas are 42 cm², 43 cm², 45 mm², and 490 mm². 2. **Convert all areas to the same unit:** To compare areas, convert all to either cm² or mm². We know that $1\text{ cm} = 10\text{ mm}$, so $1\text{ cm}^2 = 100\text{ mm}^2$. 3. **Convert cm² to mm²:** - $42\text{ cm}^2 = 42 \times 100 = 4200\text{ mm}^2$ - $43\text{ cm}^2 = 43 \times 100 = 4300\text{ mm}^2$ 4. **Compare all areas in mm²:** - $42\text{ cm}^2 = 4200\text{ mm}^2$ - $43\text{ cm}^2 = 4300\text{ mm}^2$ - $45\text{ mm}^2$ - $490\text{ mm}^2$ 5. **Determine the largest:** Clearly, $4300\text{ mm}^2$ (which is $43\text{ cm}^2$) is the largest area. **Final answer:** The largest area is $43\text{ cm}^2$.