Project Euler

Problem #26

A unit fraction contains 1 in the numerator. The decimal representation of the unit fractions with denominators 2 to 10 are given:

^(1)/_(2)0.5
^(1)/_(3)0.(3)
^(1)/_(4)0.25
^(1)/_(5)0.2
^(1)/_(6)0.1(6)
^(1)/_(7)0.(142857)
^(1)/_(8)0.125
^(1)/_(9)0.(1)
^(1)/_(10)0.1

Where 0.1(6) means 0.166666..., and has a 1-digit recurring cycle. It can be seen that ^(1)/_(7) has a 6-digit recurring cycle.

Find the value of d < 1000 for which ^(1)/_(d) contains the longest recurring cycle in its decimal fraction part.