Let S be the set of all positive integers having at most 4 digits and such that each of the digits is 0 or 1. What is the greatest prime factor of the sum of all the numbers in S?
11
19
37
59
101
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1
10, 11
100, 101, 110,111
1000, 1001, 1010, 1011, 1100, 1101, 1110, 1111
和是8888
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