When a number is divided by 3, the remainder is 2, and when divided by 7, the remainder is 2. What is the smallest number?
一个数被3除余2，被7除也余2，这个数最小是多少．
<gadget id="calculator">3 * 7</gadget>
<output>21</output>

<gadget id="calculator">21 + 2</gadget>
<output>23</output>

<result>23</result>