A glass fish tank is 50 cm long, 40 cm wide, and 30 cm high, and the water surface inside is 20 cm high. A piece of iron is put in, the iron piece sinks to the bottom of the water, and the water level rises by 3.5 cm. What is the volume of this block of iron?
一个玻璃鱼缸，长50厘米、宽40厘米、高30厘米，里面水面高20厘米．放入一块铁块，铁块沉入水底，结果水面上升了3.5厘米．这块铁块的体积是多少？
<gadget id="calculator">50 * 40 * 3.5</gadget>
<output>7_000</output>

<result>7_000</result>