When a number is divided by 30, the quotient is the smallest two-digit number and the remainder is the largest one-digit number. What is this number?
一个数除以30，商是最小的两位数，余数是最大的一位数，这个数是多少．
<gadget id="calculator">30 * 10</gadget>
<output>300</output>

<gadget id="calculator">300 + 9</gadget>
<output>309</output>

<result>309</result>