A bamboo pole is 6.4 meters long, inserted vertically into the bottom of the water, and the part above the water is 1.8 meters long. How long is the bamboo pole inserted into the water?
一根竹竿全长6.4米，竖直插入水底，露出水面的部分长1.8米．插入水中的竹竿长多少米？
<gadget id="calculator">6.4 - 1.8</gadget>
<output>4.6</output>

<result>4.6</result>