Example: 30 and 42
Factor them.
2 x 3 x 5 = 30
2 x 3 x 7 = 42
Combine the factors, eliminating duplicates.
2 x 3 x 5 x 7 = 210, the LCM
You need at least two numbers to find an LCM no matter what you use.
Precisely.
3 x 5 = 15 3 x 7 = 21 Combine the factors, eliminating duplicates. 3 x 5 x 7 = 105, the LCM
The idea is to divide numerator and denominator of a fraction by any common factors. Prime factorization is simply used to find all possible factors.
You can't find an LCM or a CF of a single number. You need at least two. The prime factorization of 71421 is 3 x 7 x 19 x 179 If you're asking about 7, 14 and 21, the LCM is 42 and the CF are 1 and 7 7 2 x 7 3 x 7
To answer GCF and LCM questions.
True.
You need at least two numbers to find an LCM no matter what you use.
In finding the LCM or HCF of two or more numbers
speed you can just use your brain to find the LCM faster, sometimes.
It doesn't matter which method you use. You still need at least two numbers to find an LCM. There is no LCM of 20.
Let's do 20 first.20 can be written as 4x5. Note that 5 is prime but 4 is not. So write 4 as 2x2.The prime factorization of 20 is 2x2x5.Now for 60, we have 3x20.We can use what we just did and write the prime factorization of 60 as2x2x3x5.
A factor tree.
To find the GCF and the LCM you have to first at least try to use prime factorization. So use factor trees. Or for the LCM find th least common multiples of the number.
837 279,3 93,3,3 31,3,3,3
The least common multiple (LCM) of 18 and 24 is 72. To find the LCM, you can list the multiples of each number or use the prime factorization method. The prime factorization of 18 is (2 \times 3^2) and for 24, it is (2^3 \times 3). Taking the highest power of each prime, the LCM is (2^3 \times 3^2 = 72).
726 363,2 121,3,2 11,11,3,2