The sum of the numbers A and B is 891. If 0 is added to the end of the number B, the two numbers are equal. What is the number A?
甲、乙两数之和是891，如果把乙数的末尾添上0，两个数就相等，则甲数是多少．
<gadget id="calculator">10 + 1</gadget>
<output>11</output>

<gadget id="calculator">891 / 11</gadget>
<output>81</output>

<gadget id="calculator">81 * 10</gadget>
<output>810</output>

<result>810</result>