There are two cylindrical glasses, A and B, whose inner diameters are 10 cm and 20 cm respectively, and the glasses contain a certain amount of water. There is an iron block sinking in cup A, when the iron block is taken out, the water level in cup A drops by 2 cm; then the iron block is submerged in cup B, and the water in cup B does not overflow. Question: How many centimeters did the water level in cup B rise at this time?
有甲、乙两只圆柱形玻璃杯，其内直径依次是10厘米、20厘米，杯中盛有适量的水．甲杯中沉没着一铁块，当取出此铁块后，甲杯中的水位下降了2厘米；然后将铁块沉没于乙杯，且乙杯中的水未外溢．问：这时乙杯中的水位上升了多少厘米？
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">3.14 * 100</gadget>
<output>314</output>

<gadget id="calculator">2 / 314</gadget>
<output>1/157 = around 0.006369</output>

<gadget id="calculator">3.14 * 25 * (1/157)</gadget>
<output>0.5</output>

<result>0.5</result>