2. Write the pure repeating (recurring) decimal number as a proper fraction.
0.7 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 = 0.7
Set up the second equation.
- Number of decimal places repeating: 1
Multiply both sides of the first equation by 101 = 10
y = 0.7
10 × y = 10 × 0.7
10 × y = 7.7
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 = 7.7 - 0.7 ⇒
(10 - 1) × y = 7.7 - 0.7 ⇒
We now have a new equation:
9 × y = 7
Solve for y in the new equation.
9 × y = 7 ⇒
y = 7/9
Let the result written as a fraction.
Now we can write the number as a fraction.
According to our first equation:
y = 0.7
According to our calculations:
y = 7/9
⇒ 0.7 = 7/9
3. Reduce (simplify) the fraction above:
7/9
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).
7 is a prime number, it cannot be factored into other prime factors
9 = 32
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 (7; 32) = 1
The numerator and the denominator are coprime numbers (no common prime factors, GCF = 1). So, the fraction cannot be reduced (simplified): irreducible fraction.