convert to fraction:
8.714285714285714285...(the 714285 is repeating.
you have six digits repeating. multiply the number by 1,000,000
8714285.714285714285
subtract the original number
-8.714285714285714285
notice the decimal portion disappears and you have 8714285-8, Work that out.
Now, since you now have 999 999 time the original number, divide what you worked out by 999 999. That is the fraction