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Last updated on November 29th, 2024

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LCM of 3 and 7

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LCM helps to solve arithmetic operations in problems with fractions and helps in scheduling or aligning cycle of events that occur frequently.

LCM of 3 and 7 for Indonesian Students
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What is the LCM of 3 and 7?

The LCM of 3 and 7 is 21 which is the smallest positive integer, a multiple of both numbers. 
 

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How to find the LCM of 3 and 7 ?

There are various methods to find the LCM, Listing method, prime factorization method and division method are explained below; 
 

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LCM of 3 and 7 using the Listing Multiples method

The LCM of 3 and 7 can be found using the following steps;


Step 1:Write down the multiples of each number:  


Multiples of 3 = 3,6,9,12,15,18,21,…


Multiples of 7 = 7,14,21,…


Step 2:find the smallest multiple from the listed multiples of 3 and 7. 


LCM(3,7) = 21


21 is divisible by 3 and 7 leaving no reminders. 
 

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LCM of 3 and 7 using the Prime Factorization

The numbers are prime factorized and their highest powers are multiplied.     


Step 1: Write the prime factors of the numbers:


Prime factorization of 3 = 3


Prime factorization of 7  = 7


Step 2:  Pick the highest power of each prime factor:


3,7


Step 3: Multiply the factors to get the LCM: 


LCM (3,13) = 3×7 = 21
 

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LCM of 3 and 7 using the Division method

Here we divide the numbers by their prime factors and multiplying the divisors to get the LCM.


Step 1: Write the numbers in a row;

Step 2:Divide the row of numbers with a number that is evenly divisible into at least one of the given numbers, and continue dividing the numbers until the last row of the results is ‘1’ and bring down the numbers has not been divisible previously.
   
Step 3: The LCM of the numbers is the product of the divisors


3×7= 21


LCM (3,7) = 21
 

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Common Mistakes and how to avoid in LCM of 3 and 7

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LCM of 3 and 7, Examples

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Problem 1

LCM of 7 and x is 21. Find x.

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Explanation

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Problem 2

Use LCM(a,b) = a×b/HCF(a,b) to find the LCM of 3 and 7.

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Explanation

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Problem 3

Runner A can complete a lap in 3 minutes, and Runner B can complete a lap in 7 minutes. When will runners A and B meet at again?

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Explanation

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FAQs on LCM of 3 and 7

1.What are the multiples of 3 and 7?

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2.What is the LCM of 3,7 and 13?

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3.What is the HCF of 3 and 7?

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4.What is the LCM of 3,5 and 7 ?

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5.Are 3 and 7 prime numbers?

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6.How can children in Indonesia use numbers in everyday life to understand LCM of 3 and 7?

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7.What are some fun ways kids in Indonesia can practice LCM of 3 and 7 with numbers?

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8.What role do numbers and LCM of 3 and 7 play in helping children in Indonesia develop problem-solving skills?

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9.How can families in Indonesia create number-rich environments to improve LCM of 3 and 7 skills?

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Important glossaries for LCM of 3 and 7

  • Multiple: A number and any integer multiplied. 

 

  • Prime Factor: A natural number (other than 1) that has factors that are one and itself.

 

  • Prime Factorization: The process of breaking down a number into its prime factors is called Prime Factorization. 

 

  • Co-prime numbers: When the only positive integer that is a divisor of them both is 1, a number is co-prime.

 

  • Relatively Prime Numbers: Numbers that have no common factors other than 1.

 

  • Fraction: A representation of a part of a whole.
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About BrightChamps in Indonesia

At BrightChamps, numbers are more than simple digits—they unlock countless opportunities! We are dedicated to helping children all over Indonesia grasp key math skills, focusing today on the LCM of 3 and 7 with an emphasis on understanding the LCM—in a way that’s fun, engaging, and easy to follow. Whether your child is calculating the speed of a roller coaster at Dunia Fantasi, tracking scores at badminton matches, or managing their allowance for the latest gadgets, mastering numbers gives them confidence for everyday tasks. Our interactive lessons keep learning fun and easy. Since kids in Indonesia learn in diverse ways, we tailor our approach to each child’s needs. From the lively streets of Jakarta to the beautiful beaches of Bali, BrightChamps brings math to life, making the LCM a fun part of every child’s learning journey!
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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.

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Fun Fact

: She loves to read number jokes and games.

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