2. Write the mixed repeating (recurring) decimal number as a proper fraction.
0.7779 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 = 0.7779
Set up the second equation.
- Number of decimal places repeating: 2
Multiply both sides of the first equation by 102 = 100
y = 0.7779
100 × y = 100 × 0.7779
100 × y = 77.79
Get the same number of decimal places as for y:
100 × y = 77.7979
Note: 77.7979 = 77.79
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.
100 × y - y = 77.7979 - 0.7779 ⇒
(100 - 1) × y = 77.7979 - 0.7779 ⇒
We now have a new equation:
99 × y = 77.02
Solve for y in the new equation.
99 × y = 77.02 ⇒
y = 77.02/99
Let the result written as a fraction.
Now we can write the number as a fraction.
According to our first equation:
y = 0.7779
According to our calculations:
y = 77.02/99
⇒ 0.7779 = 77.02/99
Get rid of the decimal places in the fraction above.
- Multiply the top and the bottom number by 100.
- 1 followed by as many 0-s as the number of digits after the decimal point.
0.7779 = (77.02 × 100)/(99 × 100)
0.7779 = 7,702/9,900
3. Reduce (simplify) the fraction above:
7,702/9,900
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).
7,702 = 2 × 3,851
9,900 = 22 × 32 × 52 × 11
Calculate the greatest (highest) common factor (divisor), GCF.
Multiply all the common prime factors by the lowest exponents.
GCF (2 × 3,851; 22 × 32 × 52 × 11) = 2
Divide both the numerator and the denominator by their GCF.
7,702/9,900 =
(2 × 3,851)/(22 × 32 × 52 × 11) =
((2 × 3,851) ÷ 2) / ((22 × 32 × 52 × 11) ÷ 2) =
3,851/(2 × 32 × 52 × 11) =
3,851/4,950