The construction site needs 1,230 tons of cement, which are transported by 5 trucks each time, and each truck carries 12 tons of cement. After these trucks have been transported 20 times, how many tons of cement are still left?
工地需要1230吨水泥，每次用5辆货车运，每辆货车载水泥12吨，这些货车运了20次后，还有多少吨水泥没有运？
<gadget id="calculator">12 * 5 * 20</gadget>
<output>1_200</output>

<gadget id="calculator">1_230 - 1_200</gadget>
<output>30</output>

<result>30</result>