If corn is grown in a rectangular field with a length of 50 meters and a width of 40 meters, if 2 kilograms of corn can be produced per square meter, how many kilograms of corn can this field produce?
在一块长50米，宽40米的长方形地里种玉米，如果每平方米产玉米2千克，这块地可产玉米多少千克？
<gadget id="calculator">50 * 40 * 2</gadget>
<output>4_000</output>

<result>4_000</result>