i need help with LCM and GCF?

Question

easy and simple for someone to understand very quickly

Answer 1

LCM means Lowest common multiple. It means, out of the two (or more) given numbers, the lowest number that each can be evenly devided by: i.e. LCM for 25 and 10 is 50. An quick way to find this is to take all of the prime factors (25 is 5*5 and 10 is 2*5), write down every set of numbers that repeats evenly between the given numbers (in this case it is only 5) and multiply by what is left over (5 and 2). You get in the multiplication 5*5*2. That equals a total of 50, and thatis your answer.
GCF is the greatest common factor. It is the largest number that can evenly multiply to give each of the given numbers. i.e. GCF for 25 and 10 is 5. Quick way to find this is, again, to take the prime factors of each (25 is 5*5 and 10 is 2*5). Take all of the prime factors that repeat evenly (in this case it is only 5), and multiply each set together (since it is only 5, the answer is 5).

LCM for 98 and 24. 98=2*7*7 24=2*2*2*3. Common repeating numbers are only one set of 2. So, you multiply 7*7*2*2*3*2=1176
GCF for 24 and 12. 24=2*2*2*3 12=2*2*3. The common factors are 2*2*3, so the GCF is 12.
Hope this helped.

Answer 2

Find the LCM of 12 and 15.
Multiples of 12 are:
12, 24. 36, 48, 60, 72, 84 , 96, 108 ,120
Multiples of 15 are :
15 30, 45, 60, 75, 90, 105, 120
Common multiples of 12 and 15 are 60 and 120
The least common multiple of 12 and 15 is 60.

GCF of 285 and
285 = 3*5*19
7429= 17*19*23
GCF is 19

Answer 3

1. Write each number in terms of multiplication of its prime factors.
2. Write down all the prime factors of all the numbers but writing that factor once which is common to all. Multiply all these prime factors. You will get LCM
3.Take out the prime factors after step 1 which are common to all. Multiply them you will get the GCF.