To determine the number of digits in the repeating cycle of a rational number with a denominator of 7, we need to find the decimal representation of fractions with a denominator of 7.
The decimal form of \( \frac{1}{7} \) is \( 0.\overline{142857} \), which indicates a repeating cycle of 6 digits (142857). Thus, any rational number with a denominator of 7 will have a repeating decimal cycle that contains at most 6 digits.
In conclusion, the repeating cycle of a repeating decimal from a rational number with a denominator of 7 can consist of 6 digits.