A cylindrical iron bucket has a bottom diameter of 4 decimeters and a height of 5 decimeters. If the water in the bucket accounts for 90% of the volume of the bucket, how many liters of water is in the bucket?
一个圆柱形铁桶，底面直径4分米，高5分米，如果桶里盛水占桶容积的90%，这桶水有多少升？
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">3.14 * 4 * 5 * (9/10)</gadget>
<output>56.52</output>

<result>56.52</result>