There are 20 people who want to go to the other side of the river. There is only one boat by the river, and only 5 people can sit on the boat at a time. How many times must the boat carry at least before they can all cross the river?
有20个人要到河的对岸去，河边只有一条小船，船上每一次只能坐5个，小船至少要载几次，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>