LCM of 40 ad 60
2026-02-28 12:58 Diff
https://brightchamps.com/en-us/math/numbers/lcm-of-40-and-60

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Last updated on August 5, 2025

LCM is applied in everyday situations like setting alarms, synchronizing traffic lights and making music. In this article we will learn about the LCM of 40 and 60.

What is the LCM of 40 and 60?

The LCM of 40 and 60 is 120. 


Let us learn how to find and apply it. 
 

How to find the LCM of 40 and 60?

We can find the LCM of 40 and 60 using, 

  • Prime factorization method 
  • Division method 

LCM of 40 and 60 using the Listing multiples method

In this method, we just list down the multiples of the numbers till we land at the first common multiple which is the smallest multiple or the LCM of the numbers.


In the case of 40 and 60,


40 = 40,80,120,...


60= 60,120,...


LCM(40,60) = 120 
 

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LCM of 40 and 60 using the prime factorization method

The numbers are factorized and their highest powers are multiplied to find the LCM 


Prime factorization of - 


40 = 2×2×2×5 


60 = 2×3×2×5


LCM(40,60) = 120 

LCM of 40 and 60 using the division method

Follow these steps to find LCM using this method; 


1.Write the numbers in a row 


2.Proceed with dividing the numbers with a factor that can be divisible by at least one of the numbers 


3.Carry forward the numbers that haven’t been divided earlier 


4.Continue division till the remainder is 1


5.Multiply the divisors in the first column to find the LCM


LCM(40,60) = 120 
 

Common mistakes and how to avoid them in LCM of 40 and 60

Here are a few common mistakes one is likely to make while trying to find the LCM. 

Problem 1

In a machine two gears are working together. One of them completes a revolution in 40 seconds and the other does it in 60 seconds. When will they both be back at the starting position and how many revolutions will the gears complete in that time?

Okay, lets begin

Prime factorization of - 


40 = 2×2×2×5 


60 = 2×3×2×5


LCM(40,60) = 120 


LCM of 40 and 60 = 120 


Number of revolutions = Machine 1 → 40/120 = 3 revolutions 


Machine 2→  60/120 = 2 revolutions

Explanation

We find when the gears will be back by finding the LCM and the number of revolutions by just dividing the LCM by the time taken for a single revolution. 
 

Well explained 👍

Problem 2

The red light blinks every 40 seconds and the green light blinks every 60 seconds. If at time t=0 they blinked together, after what percentage of one minute will they blink together?

Okay, lets begin

We find the LCM of 40 and 60 to find the time interval in seconds;


Prime factorization of - 


40 = 2×2×2×5 


60 = 2×3×2×5


LCM(40,60) = 120 


We now convert the seconds to minutes 


60 seconds = 1 minute 


120 seconds = 2 minutes 


Percentage of one minute = 60 seconds / 120 seconds × 100 = 50% 


The red and green lights will blink at 50% of the second minute. 
 

Explanation

We find the LCM and convert the result into a percentage of a minute to find how often the blinking of the lights will coincide. 
 

Well explained 👍

Problem 3

HCF(40,60) = 20. Verify the relationship between LCM, HCF, and the product of the numbers.

Okay, lets begin

To verify the relationship we use;


LCM= 120, HCF=20


HCF(a,b)×LCM(a,b)=a×b


20×120=40×60 


2400 = 2400 
 

Explanation

The LHS = RHS, the relationship stands true. 
 

Well explained 👍

FAQs on the LCM of 40 and 60

1.What is the HCF of 40 and 60?

Factors of the numbers; 


40–1,2,4,5,8,10,20,40 


60–1,2,3,4,5,6,10,12,15,20,30,60 


HCF = 20 
 

2.Find the LCM of 40,45 and 60.

40 = 2×2×2×5 


45 = 3×3×5 


60 = 2×3×2×5


LCM (40,45,60) = 360 
 

3.Find the LCM of 48 and 60.

48 = 2×2×2×2×3 


60 = 2×3×2×5


LCM(48,60) = 240 
 

4.What is the LCM of 17 and 18?

5.What is the LCM of 42 and 63?

63 = 3×3×7


42 = 3×2×7


LCM(42,63) = 126 
 

Important glossaries for the LCM of 40 and 60

  • Multiple : product of a number and a natural integer 
  • Prime factor : number one gets after prime factorizing any given number 
  • Prime factorization : the process of breaking the number into its prime factors. 

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Hiralee Lalitkumar Makwana

About the Author

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.

Fun Fact

: She loves to read number jokes and games.