LCM Basics
What does LCM mean?
The Least Common Multiple is the smallest number that two or more numbers can both divide into without a remainder.
LCM of 3 and 4
12
Buses leave every 5 and 10 minutes. When do they leave together?
LCM= 10 MINUTES
LCM 1 & 7
7
What’s the difference?
When do we use LCM?When do we use GCF?LCM or GCF: Sharing cookies evenly?LCM or GCF: Finding same ringtone timing?
LCM of 2 and 5
10
5 and 10
10
Two kids jump rope every 3 and 4 seconds. When do they jump together?
LCM=12 SECONDS
LCM 5 AND 5
5
When do we use LCM?
When you want to find when two or more events happen together again (like buses arriving, timers beeping).
When you need a common denominator to add or subtract fractions.
When you want to line things up at the same time.
LCM of 3, 6
6
LCM of 6 and 8
24
When will 3, 5, and 6 second timers beep together?
LCM = 30 SECONDS
LCM 0 AND 9
0
When do we use GCF?
When you want to divide things evenly into the biggest groups possible (like sharing cookies evenly with no leftovers).
When you want to simplify fractions.
When you want to find the biggest size that fits into things evenly.
What is a multiple?
A multiple is what you get when you multiply a number by 1, 2, 3, 4, and so on.
LCM of 9 and 12
36
Two trains meet every 12 and 18 minutes. When will they meet together?
LCM= 36 MINUTES
LCM 7 and 14
14
Sharing cookies evenly
use GCF!
If you want to split cookies into the largest equal groups without leftovers, find the GCF.
LCM of 4, 6, and 8
48
LCM of 12 and 15
60
Pizza slices: one pizza has 8 slices, another has 12 slices. How many slices to match exactly?
LCM = 24 SLICES
LCM of a prime number and 1
The multiples of 1 are all numbers, so the LCM is always the prime number itself.
Finding same ringtone timing — use LCM!
If you want to know when two phones ring at the same time again, find the LCM.