There are 6.34 tons of coal in a pile, and 5.68 tons are used up. How many tons are left?
一堆煤有6.34吨，用去了5.68吨，还剩多少吨？
<gadget id="calculator">6.34 - 5.68</gadget>
<output>0.66</output>

<result>0.66</result>