2. Write the mixed repeating (recurring) decimal number as a proper fraction.
0.85714285714 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 = 0.85714285714
Set up the second equation.
- Number of decimal places repeating: 1
Multiply both sides of the first equation by 101 = 10
y = 0.85714285714
10 × y = 10 × 0.85714285714
10 × y = 8.5714285714
Get the same number of decimal places as for y:
10 × y = 8.57142857144
Note: 8.57142857144 = 8.5714285714
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 = 8.57142857144 - 0.85714285714 ⇒
(10 - 1) × y = 8.57142857144 - 0.85714285714 ⇒
We now have a new equation:
9 × y = 7.7142857143
Solve for y in the new equation.
9 × y = 7.7142857143 ⇒
y = 7.7142857143/9
Let the result written as a fraction.
Now we can write the number as a fraction.
According to our first equation:
y = 0.85714285714
According to our calculations:
y = 7.7142857143/9
⇒ 0.85714285714 = 7.7142857143/9
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.
0.85714285714 = (7.7142857143 × 10,000,000,000)/(9 × 10,000,000,000)
0.85714285714 = 77,142,857,143/90,000,000,000
3. Reduce (simplify) the fraction above:
77,142,857,143/90,000,000,000
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).
77,142,857,143 = 11 × 7,012,987,013
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.
But, the numerator and the denominator have no common factors.
GCF (11 × 7,012,987,013; 210 × 32 × 510) = 1
The numerator and the denominator are coprime numbers (no common prime factors, GCF = 1). So, the fraction cannot be reduced (simplified): irreducible fraction.