一个自然数，把它的各个数位上的数加起来得到一个新数，称为一次操作。例如自然数7823，各位上的数之和为：7+8+2+3＝20，对20再做一次这样的操作得：2+0＝2。进行这种操作的最后结果是将这个自然数变成一个一位数。

对数1234567891011121314……373839作连续操作，最终得到的一位数是多少？

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