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The fabulous # 142857


This number, multiplied by 1, 2, 3, 4, 5, 6, 8, or 9, results in another number whose digits are in the same order as the original. But if the result is 7 digits instead of 6, just add the first to the last number to get the sequence again. Look:
142857 x 5 = 714285
142857 x 8 = 1142856, adding the extremes (1 + 6) = 7 -> 714285
Best of all, you don't have to get 142857, you can get any number with the 6 digits in this sequence, they all have this property. Look:
428571 x 2 = 857142
285714 x 3 = 857142
285714 x 9 = 2571426, summing the extremes (2 + 6) = 8 -> 857142
And if you multiply any of these numbers that have these digits in this sequence by 7 or a multiple of 7, you will find a sequence of 9. And again if there are more than 6 digits, almost all will be 9, the ones that are not added together will give 9. See:
857142 x 7 = 5999994 (5 + 4 = 9)
571428 x 49 = 27999972 (2 + 7 = 9)
714285 x 14 = 9999990 (9 + 0 = 9)