Lowest Common Multiple
ADVANCED METHOD (Not shown)
To find the lowest
common multiple
(or LCM) of 2 and 3,
first find their multiples .
List the
2x table
↓
2 3
4
6 6
e.g. L.C.M. of 25 and 30?
The prime factors of 25 are 5 x 5.
The prime factors of 30 are 2 x 3 x 5.
List the
3x table
Remove the 5 that 25 and 30
have as a COMMON prime factor.
↓
Multiply 25 by the REMAINING
prime factors of 30.
25 x 2 x 3 = 150
The LCM of 2 and 3 is
the lowest number they
have in common, which is 6.
2
3
2x
3x
2
3
4
6 6
L.C.M. is 6
8
2x
4
2x
L.C.M. is
9
7x
3x
4x
11
6x
10x
7
3x
8x
L.C.M. is
L.C.M. is
10
3x
6
3x
5x
5x
L.C.M. is
The lowest common multiple
of 25 and 30 is 150.
5
3x
www.tts-group.co.uk/flip-it
12
9x
4x
6x
L.C.M. is
13
4x
10x
2x
4x
6x
L.C.M. is
14
4x
L.C.M. is
L.C.M. is
15
2x
5x
10x
4x
16
5x
2x
3x
17
5x
L.C.M. is
L.C.M. is
L.C.M. is
18
3x
2x
4x
4x
19
6x
8x
L.C.M. is
L.C.M. is
L.C.M. is
L.C.M. is
L.C.M. is
L.C.M. is
20
21
22
23
24
25
L.C.M. is
L.C.M. is
L.C.M. is
L.C.M. is
L.C.M. is
L.C.M. is
6x