Uncle Wu packed the harvested ginger in bags of the same size, a total of 40 bags. He weighed 4 of them, and the results were 19 kg, 21 kg, 19 kg, and 22 kg. He harvested about how many kilograms of ginger in total.
吴大伯把收获的生姜装在同样大的袋子里，一共装了40袋．他称了其中的4袋，结果分别是19千克、21千克、19千克、22千克．他大约一共收获生姜多少千克．
<gadget id="calculator">20 * 40</gadget>
<output>800</output>

<result>800</result>