2. Write the mixed repeating (recurring) decimal number as an improper fraction.
9.89285714 can be written as an improper fraction.
- The numerator is larger than or equal to the denominator.
Set up the first equation.
- Let y equal the decimal number:
y = 9.89285714
Set up the second equation.
- Number of decimal places repeating: 1
Multiply both sides of the first equation by 101 = 10
y = 9.89285714
10 × y = 10 × 9.89285714
10 × y = 98.9285714
Get the same number of decimal places as for y:
10 × y = 98.92857144
Note: 98.92857144 = 98.9285714
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 = 98.92857144 - 9.89285714 ⇒
(10 - 1) × y = 98.92857144 - 9.89285714 ⇒
We now have a new equation:
9 × y = 89.0357143
Solve for y in the new equation.
9 × y = 89.0357143 ⇒
y = 89.0357143/9
Let the result written as a fraction.
Now we can write the number as a fraction.
According to our first equation:
y = 9.89285714
According to our calculations:
y = 89.0357143/9
⇒ 9.89285714 = 89.0357143/9
Get rid of the decimal places in the fraction above.
- Multiply the top and the bottom number by 10,000,000.
- 1 followed by as many 0-s as the number of digits after the decimal point.
9.89285714 = (89.0357143 × 10,000,000)/(9 × 10,000,000)
9.89285714 = 890,357,143/90,000,000
3. Reduce (simplify) the fraction above:
890,357,143/90,000,000
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).
890,357,143 = 13 × 47 × 1,457,213
90,000,000 = 27 × 32 × 57
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 (13 × 47 × 1,457,213; 27 × 32 × 57) = 1
The numerator and the denominator are coprime numbers (no common prime factors, GCF = 1). So, the fraction cannot be reduced (simplified): irreducible fraction.
4. The fraction is an improper one, rewrite it as a mixed number (mixed fraction):
- A mixed number = an integer number and a proper fraction, of the same sign.
- Example 1: 2 1/5; Example 2: - 1 3/7.
- A proper fraction = the numerator is smaller than the denominator.
890,357,143 ÷ 90,000,000 = 9, remainder = 80,357,143 ⇒
890,357,143 = 9 × 90,000,000 + 80,357,143 ⇒
890,357,143/90,000,000 =
(9 × 90,000,000 + 80,357,143) / 90,000,000 =
(9 × 90,000,000) / 90,000,000 + 80,357,143/90,000,000 =
9 + 80,357,143/90,000,000 =
9 80,357,143/90,000,000