Numeric Response Numeric Response 8. If the diameter of a sphere is $21 \mathrm{~cm}$, then, to the nearest square centimetre, its surface area is $\mathrm{cm}^{2}$. (Record your answer in the numerical-response section below.) Your answer:

Step 1 ：The diameter of the sphere is given as 21 cm.

Step 2 ：Since the radius is half of the diameter, the radius of the sphere is \(\frac{21}{2} = 10.5\) cm.

Step 3 ：The formula for the surface area of a sphere is \(4\pi r^2\), where \(r\) is the radius of the sphere.

Step 4 ：Substituting the radius into the formula, we get \(4\pi (10.5)^2\).

Step 5 ：Calculating the above expression, we find that the surface area of the sphere is approximately 1385 square centimetres.

Step 6 ：\(\boxed{1385}\) square centimetres is the surface area of the sphere, to the nearest square centimetre.