A square wheat field is 300 meters long. If an automatic rotary sprinkler irrigation device with a range of 10 meters is used for irrigation, how many such devices are needed?
一块正方形麦田边长300米，如果用射程是10米的自动旋转喷灌装置进行喷灌，大约需要多少个这样的装置？
<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<gadget id="calculator">300 / 20</gadget>
<output>15</output>

<gadget id="calculator">15 * 15</gadget>
<output>225</output>

<result>225</result>