Arrange the largest square with 1 cent coins (the same number in each row and each column), and the result is 10 coins left; if one is added to each row and each column, then 9 coins are missing. How many 1 cent coins are there?
用1分的硬币排成一个最大的正方形(每行和每列个数相同)，结果余下10枚硬币；如果每行与每列都增加一枚，那么又缺少9枚．1分硬币有多少枚？
<gadget id="calculator">9 - 1</gadget>
<output>8</output>

<gadget id="calculator">10 + 8</gadget>
<output>18</output>

<gadget id="calculator">18 / 2</gadget>
<output>9</output>

<gadget id="calculator">9 * 9</gadget>
<output>81</output>

<gadget id="calculator">81 + 10</gadget>
<output>91</output>

<result>91</result>