Sum of repeating decimals

Compute the sum of all numbers of the form 0.abc‾0.\overline{abc} (i.e. 0.abcabcabc…0.abcabcabc\dots) where a,b,ca, b, c are distinct digits from 00 to 99.

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  1. 0.abc‾=(100a+10b+c)/9990.\overline{abc}=(100a+10b+c)/999. Sum over the 10⋅9⋅810\cdot9\cdot8 distinct-digit triples.
  2. By symmetry each position sums to 72⋅45=324072\cdot45=3240; total =111⋅3240/999=111\cdot3240/999.

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