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:
21,780 = 2 × 2 × 3 × 3 × 5 × 11 × 11 = 22 × 32 × 5 × 112
21,780 is a composite number.
49,985 = 5 × 13 × 769
49,985 is a composite number.
21,780/49,985 =
(21,780 ÷ 5) / (49,985 ÷ 5) =
4,356/9,997
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.
21,780/49,985 =
(22 × 32 × 5 × 112)/(5 × 13 × 769) =
((22 × 32 × 5 × 112) ÷ 5) / ((5 × 13 × 769) ÷ 5) =
(22 × 32 × 112)/(13 × 769) =
4,356/9,997
As a decimal number:
Simply divide the numerator by the denominator, without a remainder, as shown below:
4,356/9,997 =
4,356 ÷ 9,997 =
0.435730719216 ≈
0.44