18
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Unary Numbers
We define a number as unary by d if the number becomes divisible by d after appending one or more digits '1' to its end. For example: 14 is unary by 17, because 1411 = 17 × 83. Another example: All numbers are unary by 3.
Challenger
What percentage of all positive integers is unary by 11? Provide a percentage between 0 and 100, rounded to the nearest whole number.
Mastermind
What percentage of all positive integers is unary by 77? Provide a percentage between 0 and 100, rounded to the nearest whole number.