Easy Guide to Finding HCF & LCM of 3 Numbers - 18, 24 & 27"

[Gringo123]

I've been stuydying how to work out the highest common factor and lowest common multiple of 2 numbers. I had no problems until I had to work these things out for 3 different numbers. The numbers are 18, 24 & 27.
I was able to work out that 216 is the LCM, but I cannot see how I can work out that 3 is the HCF. Can anyone explain this to me?

 

[Fightfish]

Wrong board, but I'll answer anyway (this thread will be moved right, mods?)
The technique to use is prime factorisation; factorise each of the numbers into a product of prime numbers eg. 24 = 2^3 * 3. Due to the unique properties of prime numbers, you can obtain both the LCM and HCF by simply comparing the prime factor representations of the numbers involved.

 

[icystrike]

It will be simple (=
18=2x3²
24=2³x3
27=3³

LCM simply means take the maximum degree among the all the primes.
&
HCF simply means take the minimum degree among the all the primes.

For instance LCM of 18 , 24 and 27 , we will take 2³x3³ for we see 2 to the power of 3 is the maximum degree which is taken from 24 and 3 to the power of 3 is the maximum degree as taken from 27.

HCF is the otherwise, we take the minimum degree of prime.
HCF(18,24,27)=2^{0}\times3^{1}=3Btw, Fightfish this thread is belong under what category?