# Lcm of 6 15 and 21 relationship

### Least common multiple - Wikipedia

Common multiples are multiples that two numbers have in common. These can be useful Multiples of 3: 3, 6, 9, 12, 15, 18, 21, 24, 27 Common multiples of 2 . Calculator to find Greatest Common Divisor and Least Common Multiple with detailed explanation. Probability Distributions · Z - score Calculator · Normal Distribution · T-Test Calculator · Correlation & Regression The divisiors of 45 are: 1, 3, 5, 9, 15, 45 lcm formula. Now we can find the LCM of 6 and 8 as: lcm sol. For two integers a and b, denoted LCM(a,b), the LCM is the smallest integer that is evenly divisible by both a and b. For example, LCM (2,3) = 6 and LCM (6,10).

The lowest common multiple or LCM of two or more whole numbers is the smallest of their common multiples, apart from zero. Hence write out the first few common multiples of 12 and 16, and state their lowest common multiple.

Hence write down the LCM of 12, 16 and 24? Solution a The multiples of 12 are 12, 24, 36, 48, 60, 72, 84, 96,,… The multiples of 16 are 16, 32, 48, 64, 80, 96,,… Hence the common multiples of 12 and 16 are 48, 96, ,… and their LCM is Two or more nonzero numbers always have a common multiple — just multiply the numbers together. But the product of the numbers is not necessarily their lowest common multiple.

What is the general situation illustrated here? Solution The LCM of 9 and 10 is their product The common multiples are the multiples of the LCM You will have noticed that the list of common multiples of 4 and 6 is actually a list of multiples of their LCM Similarly, the list of common multiples of 12 and 16 is a list of the multiples of their LCM This is a general result, which in Year 7 is best demonstrated by examples.

In an exercise at the end of the module, Primes and Prime Factorisationhowever, we have indicated how to prove the result using prime factorisation. This can be restated in terms of the multiples of the previous section: On the other hand, zero is the only multiple of zero, so zero is a factor of no numbers except zero. These rather odd remarks are better left unsaid, unless students insist.

### GCF & LCM word problems (video) | Khan Academy

Then after the third test, he would have done And after the fourth test, he would have done And after the fifth test, if there is a fifth test, he would do-- so this is if they have that many tests-- he would get to total questions. And we could keep going on and on looking at all the multiples of So this is probably a hint of what we're thinking about. We're looking at multiples of the numbers. We want the minimum multiples or the least multiple. So that's with Luis.

Well what's going on with William?

## Relationship between H.C.F. and L.C.M.

Will William's teacher, after the first test, they're going to get to 24 questions. Then they're going to get to 48 after the second test. Then they're going to get to 72 after the third test.

Then they're going to get to I'm just taking multiples of They're going to get to 96 after the fourth test. And then after the fifth test, they're going to get to And if there's a sixth test, then they would get to And we could keep going on and on in there.

But let's see what they're asking us. What is the minimum number of exam questions William's or Luis's class can expect to get in a year? Well the minimum number is the point at which they've gotten the same number of exam questions, despite the fact that the tests had a different number of items.

And you see the point at which they have the same number is at This happens at They both could have exactly questions even though Luis's teacher is giving 30 at a time and even though William's teacher is giving 24 at a time.

And so the answer is And notice, they had a different number of exams. Luis had one, two, three, four exams while William would have to have one, two, three, four, five exams.

But that gets them both to total questions. Now thinking of it in terms of some of the math notation or the least common multiple notation we've seen before, this is really asking us what is the least common multiple of 30 and And that least common multiple is equal to Now there's other ways that you can find the least common multiple other than just looking at the multiples like this. You could look at it through prime factorization. So we could say that 30 is equal to 2 times 3 times 5.

And that's a different color than that blue-- 24 is equal to 2 times So 24 is equal to 2 times 2 times 2 times 3. So another way to come up with the least common multiple, if we didn't even do this exercise up here, says, look, the number has to be divisible by both 30 and If it's going to be divisible by 30, it's going to have to have 2 times 3 times 5 in its prime factorization.

That is essentially So this makes it divisible by And say, well in order to be divisible by 24, its prime factorization is going to need 3 twos and a 3.

### Multiples and Factors

Well we already have 1 three. And we already have 1 two, so we just need 2 more twos. So 2 times 2. So this makes it-- let me scroll up a little bit-- this right over here makes it divisible by And so this is essentially the prime factorization of the least common multiple of 30 and You take any one of these numbers away, you are no longer going to be divisible by one of these two numbers.

## LCM Calculator - Least Common Multiple

If you take a two away, you're not going to be divisible by 24 anymore. If you take a two or a three away. If you take a three or a five away, you're not going to be divisible by 30 anymore.

And so if you were to multiply all these out, this is 2 times 2 times 2 is 8 times 3 is 24 times 5 is Now let's do one more of these.