It is the product of multiplying 9 and a one-digit number. The number in the tens place is twice that in the ones place. What is this number?
它是9与一位数相乘的积，它十位上的数是个位上的2倍，这个数是多少．
<gadget id="calculator">9 * 1 * 7</gadget>
<output>63</output>

<result>63</result>