2. Write the mixed repeating (recurring) decimal number as a proper fraction.
0.12908 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 = 0.12908
Set up the second equation.
- Number of decimal places repeating: 1
Multiply both sides of the first equation by 101 = 10
y = 0.12908
10 × y = 10 × 0.12908
10 × y = 1.2908
Get the same number of decimal places as for y:
10 × y = 1.29088
Note: 1.29088 = 1.2908
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 = 1.29088 - 0.12908 ⇒
(10 - 1) × y = 1.29088 - 0.12908 ⇒
We now have a new equation:
9 × y = 1.1618
Solve for y in the new equation.
9 × y = 1.1618 ⇒
y = 1.1618/9
Let the result written as a fraction.
Now we can write the number as a fraction.
According to our first equation:
y = 0.12908
According to our calculations:
y = 1.1618/9
⇒ 0.12908 = 1.1618/9
Get rid of the decimal places in the fraction above.
- Multiply the top and the bottom number by 10,000.
- 1 followed by as many 0-s as the number of digits after the decimal point.
0.12908 = (1.1618 × 10,000)/(9 × 10,000)
0.12908 = 11,618/90,000
3. Reduce (simplify) the fraction above:
11,618/90,000
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).
11,618 = 2 × 37 × 157
90,000 = 24 × 32 × 54
Calculate the greatest (highest) common factor (divisor), GCF.
Multiply all the common prime factors by the lowest exponents.
GCF (2 × 37 × 157; 24 × 32 × 54) = 2
Divide both the numerator and the denominator by their GCF.
11,618/90,000 =
(2 × 37 × 157)/(24 × 32 × 54) =
((2 × 37 × 157) ÷ 2) / ((24 × 32 × 54) ÷ 2) =
(37 × 157)/(23 × 32 × 54) =
5,809/45,000