A rectangular vegetable field has a base of 450 meters and a height of 200 meters. How many hectares does this vegetable field have?
一块平形四边形的菜地，底是450米，高是200米，这块菜地有多少公顷．
<gadget id="calculator">450 * 200</gadget>
<output>90_000</output>

<gadget id="calculator">90_000 / 10_000</gadget>
<output>9</output>

<result>9</result>