How many digits long could the repeating cycle of a repeating decimal be if the denominator of the rational number is 7? A. Up to 7 digits long b. Up to 6 digits long c. Any finite length d. Infinitely long
The repeating cycle of a repeating decimal can be at most one less than the denominator of the rational number. In this case, the denominator is 7, so the repeating cycle can be at most 7-1=<<7-1=6>>6 digits long.
Therefore, the answer is $\boxed{\text{(b)}}$ "Up to 6 digits long."