20 people are waiting by the river to cross the river to the other side. There is only one empty boat by the river, and there can only be 5 people on the boat at a time. How many batches must they divide to cross the river?
20人在河边等待渡河到对岸去，河边只有一条空船，船上每次只能坐5人，他们至少要分多少批才能全部过河？
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<result>5</result>