8 meters 90 centimeters = how many millimeters.
8米90厘米=多少毫米．
<gadget id="calculator">8 * 1_000</gadget>
<output>8_000</output>

<gadget id="calculator">90 * 10</gadget>
<output>900</output>

<gadget id="calculator">8_000 + 900</gadget>
<output>8_900</output>

<result>8_900</result>