Last updated on May 26th, 2025
The meaning of least common factor (LCM) is to find the smallest number that divides any two integers evenly. LCM is used mainly in fractions to find a common number for both the integers. We use LCM for solving problems, lining up cycles or even synchronizing of events, also to schedule tasks in everyday life.
We use LCM of 24 and 90, to find the smallest number that divides both the numbers equally. The smallest positive number is the number that divides both numbers equally, is 360 without leaving any remainder. LCM is used mainly in fractions to find a common number for both the integers.
The LCM of 24 and 90 can be found by the following methods like division method, listing multiples, prime factorization.
In division method, we divide both the numbers, we begin with dividing side by side the smallest number. We continue dividing until we get a common number that divides both the numbers equally. It makes it easier for the children to focus on prime factors and identify them.
Now multiply the divisors : 2×2×3×3×5×5=360 which is the LCM.
Step 1: Start by listing multiples of both the numbers separately:
Multiples of 24 are 24,48,72,96,120,144,168,192,216,240,264,288,312,336,360…..
Multiples of 90 are 90,180,270,360,450…..
Step 2: The least common factor from the list is 360.
Therefore, the LCM of 24 and 90 is 360.
Step 1:We part both the numbers unto factors:
Factor of 24: 23 × 31
Factors of 90: 32×5x2
Step 2:Take the powers of both the numbers and multiply together:
LCM=23x32x5=360.
While solving problems based on the LCM of 24 and 90, children fail to understand few concepts, to give an idea of the mistakes,given below are a few mistakes and solutions of how to avoid them:
If the LCM of 24 and a number x is 360, find the value of x.
Answer: x=90
LCM (a, b) x GCD(a, b)=axb
LCM(24,x)=360
a=24
GCD(24,x)=6(since x shares factors with 24)
By using the formula:
360 x 6 = 24 x x
2160=24x x
x = 2160/24=90
Prove that the following relationship holds for 24 and 90: LCM (24,90) x GCD(24,90)= 24 × 90
Prime factorization:
24= 23 × 3
90= 2 × 32 × 5
LCM (24,90):
Select highest powers of all prime factors:
23 × 32 × 5 =360.
GCD (24,90):
Take LCM of the common factors:
2 × 3=6
Verifying the relationship:
LCM (24,90) x GCD(24,90)= 360 × 6=2160
24 × 90 = 2160
Both sides are equal.
Two traffic lights blink at intervals of 24 seconds and 90 seconds, respectively. If both lights start blinking together, after how many seconds will they blink together again?
To find when the two lights will blink together, we need to calculate the LCM of the numbers 24and 90
LCM of 24 and 90
Prime factors of 24: 23× 3
Prime factors of 90: 32×5x2
LCM = 23×32×5=360
Therefore, the two lights will blink together again after 360 seconds.
A student organization meets every 24 days, and the parent-teacher organization meets every 90 days. When will both the organization meet together again?
LCM of 24and 90
Prime factors of 24 : 23×3
Prime factors of 90: 32 × 2 × 5
LCM = 23×32×5=360
The two lights will blink together again after 360 seconds.
Simplify the expression:
solution:
24/360+90/360
Simplify each fraction 24/360 =1/15 , 90/360= 1/4
Add the fractions 1/15+1/4
LCM(15,4)=60, rewriting them we get,
1/15=4/60 , 1/4=15/60
Add the fractions:
4/60+15/60=19/60
Thus, the simplified expression is: 19/60
Hiralee Lalitkumar Makwana has almost two years of teaching experience. She is a number ninja as she loves numbers. Her interest in numbers can be seen in the way she cracks math puzzles and hidden patterns.
: She loves to read number jokes and games.