What is the number composed of 5 hundreds, 8 ones, 4 tenths, and 1 thousandth.
由5个百，8个一，4个十分之一，1个千分之一组成的数是多少．
<gadget id="calculator">1 / 1_000</gadget>
<output>1/1_000 = around 0.001</output>

<gadget id="calculator">500 + 8 + 0.4 + (1/1_000)</gadget>
<output>508.401</output>

<result>508.401</result>