The tens digit is 1, and the ones digit is 8 more than the tens digit. What is this number?
十位上是1，个位上的数比十位上多8，这个数是多少．
<gadget id="calculator">1 * 10</gadget>
<output>10</output>

<gadget id="calculator">8 + 1</gadget>
<output>9</output>

<gadget id="calculator">10 + 9</gadget>
<output>19</output>

<result>19</result>