If the side length of a square is 8 cm, if its side length is increased by 1 cm, how much will its area increase?
一个正方形的边长是8厘米，如果把它的边长增加1厘米，那么它的面积增加多少．
<gadget id="calculator">8 + 1</gadget>
<output>9</output>

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

<gadget id="calculator">8 * 8</gadget>
<output>64</output>

<gadget id="calculator">81 - 64</gadget>
<output>17</output>

<result>17</result>