Let's solve each conversion step-by-step.

A) 825 acres to hectares

1 acre is approximately equal to 0.404686 hectares.

$825 \text{ acres} \times 0.404686 \, \text{hectares/acre} = 333.86445 \, \text{hectares}$

So, 825 acres is approximately 333.86 hectares.

B) 3905 cm² to m²

1 square meter (m²) is equal to $10,000 \, \text{cm}^2$.

$3905 \, \text{cm}^2 \div 10,000 = 0.3905 \, \text{m}^2$

So, 3905 cm² is equal to 0.3905 m².

Would you like more details on any of these conversions?

---

Related Questions:

1. How do you convert hectares to acres?
2. What other units are commonly used to measure area?
3. How many square meters are there in 1 square kilometer?
4. What is the area of a circle with a radius of 10 cm in m²?
5. How do you convert square inches to square feet?

Tip:

For area conversions, remember that the conversion factor needs to be squared when converting between squared units, such as cm² to m².