Maths LCM

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oxyeleven
Posts: 4
Joined: Fri Sep 26, 2014 9:34 pm

Maths LCM

Post by oxyeleven »

This may sound very basic but still thought of posting

what is LCM of 3 & 9, is it 9 or 18
bridge
Posts: 262
Joined: Tue Feb 12, 2013 1:38 am

Re: Maths LCM

Post by bridge »

9

3 x 3 = 9
1 x 9 = 9
oxyeleven
Posts: 4
Joined: Fri Sep 26, 2014 9:34 pm

Re: Maths LCM

Post by oxyeleven »

my answer is also 9
but it seems 18 is LCM of 3 and 9, this was told to my kid

3 6 9 12 15 18

9 18 27 36

hence 18
ToadMum
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Location: Essex

Re: Maths LCM

Post by ToadMum »

oxyeleven wrote:my answer is also 9
but it seems 18 is LCM of 3 and 9, this was told to my kid

3 6 9 12 15 18

9 18 27 36

hence 18
But in that example, the series still intersect at 9...?
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oxyeleven
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Joined: Fri Sep 26, 2014 9:34 pm

Re: Maths LCM

Post by oxyeleven »

yes answer is 9 to me also.
Guest55
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Joined: Mon Feb 12, 2007 2:21 pm

Re: Maths LCM

Post by Guest55 »

oxyeleven wrote:my answer is also 9
but it seems 18 is LCM of 3 and 9, this was told to my kid

3 6 9 12 15 18

9 18 27 36

hence 18
Wrong - it is 9 [Graduate mathematician and qualified teacher] - LOWEST common multiple
Mathsatish
Posts: 10
Joined: Fri Dec 11, 2020 12:48 pm

Re: Maths LCM

Post by Mathsatish »

LCM means lowest common multiple
IF they asked what is the LCM of 3,9

Multiples of 3 are 3,6,9,12,15,18,21,24,27,30
Multiples of 9 are 9,18,27,36,45,54,63,72,81,90

Common multiples of 3,9 are 9,18,27,36,45,54,63,72,81,90

Among the common multiples what is the lowest common multiple of 3,9?..Answer is 9..
18 is a common multiple of 3,9 but not the lowest common multiple..

If there are two numbers A,B, A is a smaller number and B is a bigger number.
If A goes into B then the LCM of A,B is B

Examples : LCM of 3,15 answer is 15
Lcm of 4,16 Answer is 16...
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