How many consecutive 0.5s are subtracted from 10, leaving 2.5.
从10里连续减去多少个0.5，还剩2.5．
<gadget id="calculator">10 - 2.5</gadget>
<output>7.5</output>

<gadget id="calculator">7.5 / 0.5</gadget>
<output>15</output>

<result>15</result>