2. Write the pure repeating (recurring) decimal number as an improper fraction.
38.9 can be written as an improper fraction.
- The numerator larger than or equal to the denominator.
Set up the first equation.
- Let y equal the decimal number:
y = 38.9
Set up the second equation.
- Number of decimal places repeating: 1
Multiply both sides of the first equation by 101 = 10
y = 38.9
10 × y = 10 × 38.9
10 × y = 389.9
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 = 389.9 - 38.9 ⇒
(10 - 1) × y = 389.9 - 38.9 ⇒
We now have a new equation:
9 × y = 351
Solve for y in the new equation.
9 × y = 351 ⇒
y = 351/9
Let the result written as a fraction.
Now we can write the number as a fraction.
According to our first equation:
y = 38.9
According to our calculations:
y = 351/9
⇒ 38.9 = 351/9
3. Reduce (simplify) the fraction above:
351/9
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).
351 = 33 × 13
9 = 32
Calculate the greatest (highest) common factor (divisor), GCF.
Multiply all the common prime factors by the lowest exponents.
GCF (33 × 13; 32) = 32
Divide both the numerator and the denominator by their GCF.
351/9 =
(33 × 13)/32 =
((33 × 13) ÷ 32) / (32 ÷ 32) =
(3 × 13)/1 =
39/1
Note:: 39/1 = 39