To reduce a fraction to the lowest terms equivalent: divide the numerator and denominator by their greatest common factor, GCF
To calculate the greatest common factor, GCF:
- 1. Factor the numerator and the denominator (into prime factors), build their prime factorizations.
- 2. Multiply all their common prime factors, taken by the lowest exponents.
1. Factor the numerator and the denominator:
To factor a number (into prime factors) - or, in other words, to break it down to prime factors - or, in other words, to build its prime factorization: find the prime numbers that multiply together to get that number.
The prime factorizations:
Written with exponents:
123,720 = 2 × 2 × 2 × 3 × 5 × 1,031 = 23 × 3 × 5 × 1,031
123,720 is a composite number.
1,031 is a prime number, it cannot be factored (into other prime factors).
123,720/1,031 =
(123,720 ÷ 1,031) / (1,031 ÷ 1,031) =
120/1 =
120
* When it's 1, the denominator of the fraction can be omitted.
Yet another method to reduce the fraction
To reduce a fraction without calculating the GCF: factor its numerator and denominator, then all the common prime factors are easily identified and crossed out.
123,720/1,031 =
(23 × 3 × 5 × 1,031)/1,031 =
((23 × 3 × 5 × 1,031) ÷ 1,031) / (1,031 ÷ 1,031) =
(23 × 3 × 5)/1 =
(23 × 3 × 5) =
120
* When it's 1, the denominator of the fraction can be omitted.