In the concrete used for construction, the ratio of cement, sand and stone is 2:3:5, so how many kilograms of cement is in 1 ton of concrete.
建筑用的混凝土中，水泥、沙子、石子的比为2：3：5，那么1吨混凝土中有水泥多少千克．
<gadget id="calculator">2 + 3 + 5</gadget>
<output>10</output>

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 * (3/10) * 1_000</gadget>
<output>300</output>

<result>300</result>