2. Write the mixed repeating (recurring) decimal number as a proper fraction.
0.85714285716 can be written as a proper fraction.
- The numerator is smaller than the denominator.
Set up the first equation.
- Let y equal the decimal number:
y = 0.85714285716
Set up the second equation.
- Number of decimal places repeating: 1
Multiply both sides of the first equation by 101 = 10
y = 0.85714285716
10 × y = 10 × 0.85714285716
10 × y = 8.5714285716
Get the same number of decimal places as for y:
10 × y = 8.57142857166
Note: 8.57142857166 = 8.5714285716
Subtract the first equation from the second one.
- Having the same number of decimal places ...
- The repeating pattern drops off by subtracting the two equations.
10 × y - y = 8.57142857166 - 0.85714285716 ⇒
(10 - 1) × y = 8.57142857166 - 0.85714285716 ⇒
We now have a new equation:
9 × y = 7.7142857145
Solve for y in the new equation.
9 × y = 7.7142857145 ⇒
y = 7.7142857145/9
Let the result written as a fraction.
Now we can write the number as a fraction.
According to our first equation:
y = 0.85714285716
According to our calculations:
y = 7.7142857145/9
⇒ 0.85714285716 = 7.7142857145/9
Get rid of the decimal places in the fraction above.
- Multiply the top and the bottom number by 10,000,000,000.
- 1 followed by as many 0-s as the number of digits after the decimal point.
0.85714285716 = (7.7142857145 × 10,000,000,000)/(9 × 10,000,000,000)
0.85714285716 = 77,142,857,145/90,000,000,000
3. Reduce (simplify) the fraction above:
77,142,857,145/90,000,000,000
to the lowest terms, to its simplest equivalent form, irreducible.
To reduce a fraction to the lowest terms divide the numerator and denominator by their greatest (highest) common factor (divisor), GCF.
Factor the numerator and denominator (prime factorization).
77,142,857,145 = 3 × 5 × 37 × 4,481 × 31,019
90,000,000,000 = 210 × 32 × 510
Calculate the greatest (highest) common factor (divisor), GCF.
Multiply all the common prime factors by the lowest exponents.
GCF (3 × 5 × 37 × 4,481 × 31,019; 210 × 32 × 510) = 3 × 5
Divide both the numerator and the denominator by their GCF.
77,142,857,145/90,000,000,000 =
(3 × 5 × 37 × 4,481 × 31,019)/(210 × 32 × 510) =
((3 × 5 × 37 × 4,481 × 31,019) ÷ (3 × 5)) / ((210 × 32 × 510) ÷ (3 × 5)) =
(37 × 4,481 × 31,019)/(210 × 3 × 59) =
5,142,857,143/6,000,000,000