2. Write the number as an improper fraction.
- 312.8 can be written as an improper fraction.
- An improper fraction = the numerator is larger than or equal to the denominator..
Write down the number divided by 1, as a fraction:
312.8 = 312.8/1
Turn the top number into a whole number.
- Multiply both the top and the bottom by the same number.
- This number is: 10.
- 1 followed by as many 0-s as the number of digits after the decimal point.
312.8/1 =
(312.8 × 10)/(1 × 10) =
3,128/10
3. Reduce (simplify) the fraction above:
3,128/10
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).
3,128 = 23 × 17 × 23
10 = 2 × 5
Calculate the greatest (highest) common factor (divisor), GCF.
Multiply all the common prime factors by the lowest exponents.
GCF (23 × 17 × 23; 2 × 5) = 2
Divide both the numerator and the denominator by their GCF.
3,128/10 =
(23 × 17 × 23)/(2 × 5) =
((23 × 17 × 23) ÷ 2) / ((2 × 5) ÷ 2) =
(22 × 17 × 23)/5 =
1,564/5
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.
1,564 ÷ 5 = 312, remainder = 4 ⇒
1,564 = 312 × 5 + 4 ⇒
1,564/5 =
(312 × 5 + 4) / 5 =
(312 × 5) / 5 + 4/5 =
312 + 4/5 =
312 4/5