奇特的算法：我们常常会遇到被减数与减数的个位、十位上的数字正好互换的题目，如：91-19，82-18，73-37等。

计算这一类题目有一种特殊的简便方法，只要用被减数十位上的数字与个位上数字的差乘9，就可以得到结果。

比如：73-37，可以这样算：7-3=4　→　4×9=36　→　73-37=36。神奇吧！你也来试试吧！

找几道这样的题目，用上面的方法算一算，看看是否真的与正确的得数相同。

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