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To add to my previous thinking I beleive that the LCD of 98, 14 and 20 is 490. I don't see how you can reach this result be multiplying using the higher powers of teh repeated primes.

To add to my previous thinking I beleive that the LCD of 98, 14 and 20 is 490. I don't see how you can reach this result be multiplying using the higher powers of teh repeated primes.

LCM[98,14,20]

98 = 7*7*2

14 = 2*7

20 = 2*5*2

LCM = 7*7*2*2*5 = 980

you forgot to count the five !

Last edited by KillerSquirrel on 06 Sep 2007, 08:46, edited 2 times in total.

Ok, maybe I'm retarded or something but I still do not get it. According to what is mentioned in the previous posts regarding this thread, I should multiply the higher powers of the repeated primes.

KillerSquirrel, I do not get you

98 = 7*7*2. I guess the repeated primes here are 7*7
14 = 2*7. No repeated primes here.
20 = 2*2*5. Repeated numbers are 2*2 but they are not primes...

Ok, maybe I'm retarded or something but I still do not get it. According to what is mentioned in the previous posts regarding this thread, I should multiply the higher powers of the repeated primes.

KillerSquirrel, I do not get you

98 = 7*7*2. I guess the repeated primes here are 7*7 14 = 2*7. No repeated primes here. 20 = 2*2*5. Repeated numbers are 2*2 but they are not primes...

How can you say then that LCM = 7*7*2*5 ??

Now I'm even more confused

Don't be !

LCM
---
The least common multiple of two (or more) numbers is the product of
one number times the factors of the other number(s) that aren't
common.

If you wanted to find the least common multiple of 32 and 76, you'd
multiply 32 by 19, because 19 is the only factor of 76 that isn't
common to the factors of 32.

In the same way the least common multiple of 98,14,20 = 98*5*2 = 980

Last edited by KillerSquirrel on 06 Sep 2007, 08:47, edited 1 time in total.

KillerSquirrel I get what you said and I would like to thank you for your explanation. I have a last question however.

As you explained before, we must use the higher power of the repeated primes:

98 = 7*7*2
20 = 2*2*5
14 = 2*7

Ok. Prime number 7 appears in 98 2 times (higher power). Prime number 2 appears twice in 20 (higher power).

Why then LCD is not 7*7*2*2*5? Why do not we multiply 2*2 and instead only once? Isn't it the higher repeated power? I know that this gives a result of 980, which is wrong, but why does the rule not work here? It works on all the other examples in this thread.

I hope it is too annoying for you. In that case I apologize anyway.

KillerSquirrel I get what you said and I would like to thank you for your explanation. I have a last question however.

As you explained before, we must use the higher power of the repeated primes:

98 = 7*7*2 20 = 2*2*5 14 = 2*7

Ok. Prime number 7 appears in 98 2 times (higher power). Prime number 2 appears twice in 20 (higher power).

Why then LCD is not 7*7*2*2*5? Why do not we multiply 2*2 and instead only once? Isn't it the higher repeated power? I know that this gives a result of 980, which is wrong, but why does the rule not work here? It works on all the other examples in this thread.

I hope it is too annoying for you. In that case I apologize anyway.

You are correct ! the LCM is indeed 980 not 490 - my posts have been corrected.