How do you decide by which power of 10 to multiply an equation when writing a decimal with repeating digits

Terminating and Repeating Decimals. Any rational number (that is, a fraction in lowest terms) can be written as either a terminating decimal or a repeating decimal . Just divide the numerator by the denominator . ... Otherwise, the remainders will begin to repeat after some point, and you have a repeating decimal.

7. d. 64

8. i. 32

9. c. 125

10. j. none of the above

11. d. 81

12. i. 216

13. e. none of the above

14. g. 240

15. e. none of the above

16. g. 32

17.   e. none of the above

i believe it is c.y = 9x

rise over run. 9 units up over 1 unit right or 9/1