Uncle Wang's family planted 5 rows of pear trees, each with 8 trees. This year, each pear tree harvested an average of 42 kg of pears. How many kilograms of pears did Uncle Wang's family harvest this year?
王叔叔家种了5行梨树，每行8棵，今年平均每棵梨树收获梨42千克．今年王叔叔家一共收获梨多少千克？
<gadget id="calculator">8 * 5 * 42</gadget>
<output>1_680</output>

<result>1_680</result>