800 tons of ore are used to smelt iron, and 400 tons of iron are smelted. What is the iron content of this ore?
用800吨矿石炼铁，炼出铁400吨，这种矿石的含铁率是多少．
<gadget id="calculator">400 / 800</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">100 / 100</gadget>
<output>1</output>

<gadget id="calculator">(1/2) * 1</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>