What is the sum of the mantissas of all four-digit numbers divisible by 6?
所有能被6整除的四位数的尾数之和是多少．
<gadget id="calculator">2 + 8 + 4 + 0 + 6</gadget>
<output>20</output>

<gadget id="calculator">9_996 - 1_002</gadget>
<output>8_994</output>

<gadget id="calculator">8_994 / 6</gadget>
<output>1_499</output>

<gadget id="calculator">1_499 + 1</gadget>
<output>1_500</output>

<gadget id="calculator">1_500 / 5</gadget>
<output>300</output>

<gadget id="calculator">20 * 300</gadget>
<output>6_000</output>

<result>6_000</result>