Taking "ten thousand" as the unit, what is the maximum difference between the exact number 20,000 and the approximate number of 20,000?
以"万"为单位，准确数2万与近似数2万比较，最多相差多少．
<gadget id="calculator">2 * 10_000</gadget>
<output>20_000</output>

<gadget id="calculator">20_000 - 15_000</gadget>
<output>5_000</output>

<result>5_000</result>