Go to navigation
It is currently Fri Dec 09, 2016 11:17 pm

All times are UTC




Post new topic Reply to topic  [ 3 posts ] 
Author Message
PostPosted: Sun Sep 23, 2007 10:35 pm 
Offline

Joined: Fri Sep 07, 2007 1:12 pm
Posts: 151
I was wondering if anyone has any tips/formula for working out Lowest common multiples, highest common factors etc. My daughter gets the right answer most of the time but takes a long while doing it.


Top
 Profile  
 
 Post subject:
PostPosted: Mon Sep 24, 2007 8:04 am 
Offline

Joined: Thu Jan 12, 2006 3:29 pm
Posts: 625
Hi Silver29

The quickest way if the number can not be identified immediately is to use prime factors

i.e 2, 3, 5, 7, 11 etc

Any number can be written as a product of their primes

i.e 6 can be made by multiplying 2 x 3 (both prime numbers)

Work out prime factors as follows:

28
divide by 2
14
divide by 2
7
is a prime number

28 is 2 x 2 x 7

36
divide by 2
18
divide by 2
9
divide by 3
3
is a prime number

36 is 2 x 2 x 3 x 3

Place both sets of numbers closer together

28 = 2 x 2 x 7
36 = 2 x 2 x 3 x 3

The highest common factor is the highest number that goes exactly into both numbers.

The common factors in the example are 2 x 2
Therefore the highest common factor is 4
4 goes into 28, 7 times
4 goes into 36, 9 times

The lowest common multiple is the lowest number that both the numbers will go into.

For lowest common multiple we only count a common value once

28 = 2 x 2 x 7
36 = 2 x 2 x 3 x 3

The lowest common multiple is

2 x 2 x 3 x 3 x 7 = 252

28 goes into 252, 9 times
36 goes into 252, 7 times

Hope this helps

Regards

Mike


Top
 Profile  
 
 Post subject:
PostPosted: Mon Sep 24, 2007 11:29 am 
Offline

Joined: Fri Sep 07, 2007 1:12 pm
Posts: 151
Mike, thanks so much for the step by step explanation - it really makes sense now. :)


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 3 posts ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
CALL 020 8204 5060
   
Privacy Policy | Refund Policy | Disclaimer | Copyright © 2004 – 2016