The formula for the volume of a cone ($V$) is $V = \frac{1}{3} \pi r^2 h$, where $r$ is the radius of the base and $h$ is the height. Given: Radius ($r$) = 21 cm Height ($h$) = 20 cm Using $\pi = \frac{22}{7}$:$V = \frac{1}{3} \times \frac{22}{7} \times (21\text{ cm})^2 \times 20\text{ cm}$ $V = \frac{1}{3} \times \frac{22}{7} \times 21 \times 21 \times 20$ We can simplify the calculation: $V = \frac{1}{3} \times 22 \times \left(\frac{21}{7}\right) \times 21 \times 20$ $V = \frac{1}{3} \times 22 \times 3 \times 21 \times 20$Cancel out the $3$ in the denominator and numerator:$V = 22 \times 21 \times 20$First, calculate $22 \times 21$:$22 \times 21 = 462$Now, multiply by $20$:$V = 462 \times 20 = 9240$Therefore, the volume of the cone is $9240$ cubic cm.