A rectangular wheat field is 100 meters long and 60 meters wide. If an automatic rotating sprinkler irrigation device with a spray distance of 10 meters is used for irrigation, how many such sprinkler irrigation devices are needed?
一块长方形麦田的长是100米，宽60米，如果用喷程是10米的自动旋转喷灌装置进行灌溉，大约需要多少个这样的喷灌装置？
<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<gadget id="calculator">100 / 20</gadget>
<output>5</output>

<gadget id="calculator">60 / 20</gadget>
<output>3</output>

<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<result>15</result>