Adding 60 to a natural number is a perfect square number. If adding 43 is also a perfect square number, what is the natural number?
一个自然数加上60，则为一个完全平方数，如果加上43也是一个完全平方数，这个自然数是多少．
<gadget id="calculator">9 ** 2</gadget>
<output>81</output>

<gadget id="calculator">81 - 60</gadget>
<output>21</output>

<result>21</result>