20 trees are planted in each row, and 10 rows are to be planted. 4 yuan per sapling, how much does it cost in total?
每行种20棵树，要种10行．每棵树苗4元钱，一共需要多少钱？
<gadget id="calculator">20 * 10 * 4</gadget>
<output>800</output>

<result>800</result>