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:
123,760 = 2 × 2 × 2 × 2 × 5 × 7 × 13 × 17 = 24 × 5 × 7 × 13 × 17
123,760 is a composite number.
Written with exponents:
280 = 2 × 2 × 2 × 5 × 7 = 23 × 5 × 7
280 is a composite number.
123,760/280 =
(123,760 ÷ 280) / (280 ÷ 280) =
442/1 =
442
* 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.
123,760/280 =
(24 × 5 × 7 × 13 × 17)/(23 × 5 × 7) =
((24 × 5 × 7 × 13 × 17) ÷ (23 × 5 × 7)) / ((23 × 5 × 7) ÷ (23 × 5 × 7)) =
(2 × 13 × 17)/1 =
(2 × 13 × 17) =
442
* When it's 1, the denominator of the fraction can be omitted.