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:
21 = 3 × 7
21 is a composite number.
Written with exponents:
4,000,000,041 = 3 × 3 × 709 × 626,861 = 32 × 709 × 626,861
4,000,000,041 is a composite number.
21/4,000,000,041 =
(21 ÷ 3) / (4,000,000,041 ÷ 3) =
7/1,333,333,347
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.
21/4,000,000,041 =
(3 × 7)/(32 × 709 × 626,861) =
((3 × 7) ÷ 3) / ((32 × 709 × 626,861) ÷ 3) =
7/(3 × 709 × 626,861) =
7/1,333,333,347
As a decimal number:
Simply divide the numerator by the denominator, without a remainder, as shown below:
7/1,333,333,347 =
7 ÷ 1,333,333,347 =
0.00000000525 ≈
0