A measuring cylinder is filled with 400ml of water. After putting 4 steel balls with equal radii, the water level rises to 480ml. What is the volume of each steel ball in cubic centimeters?
一个量筒，盛有400毫升的水，放入4颗半径相等的钢珠后，水面上升到480毫升的地方．每颗钢珠的体积是多少立方厘米？
<gadget id="calculator">480 - 400</gadget>
<output>80</output>

<gadget id="calculator">80 / 4</gadget>
<output>20</output>

<result>20</result>