Find the smallest integer m for which there are positive integers n>k>1 satisfying the equation n11…1=k11…1⋅m.
Solution
Obviously m>9. If m=ab, where a≥1 then we must have b=1 to ensure last digit of 1⋅m is equal 1. In this case regardless of value of a the second last digit of k11…1⋅m is equal to the last digit of a+1 and can't be equal 1. So m≥100. Obviously m=100 doesn't satisfy to the condition, but m=101 satisfies, since 11⋅101=1111. Hence, the answer to this problem is m=101. □
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Source: MathNet,
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