When Liangliang was doing a calculation problem of multiplying two numbers, due to carelessness, he regarded a factor of 7 as 9, and the resulting product was 819. Do you know the correct product?
亮亮在做一道两个数相乘的计算题时，由于马虎，把一个因数7看作了9，结果得到的积是819，你知道正确的积是多少吗？
<gadget id="calculator">819 / 9</gadget>
<output>91</output>

<gadget id="calculator">91 * 7</gadget>
<output>637</output>

<result>637</result>