When a number is divided by 20, the quotient is 20 and the remainder is 10. What is the number?
一个数除以20，商是20，余数是10，这个数是多少．
<gadget id="calculator">20 * 20</gadget>
<output>400</output>

<gadget id="calculator">400 + 10</gadget>
<output>410</output>

<result>410</result>