292 LearnersLast updated on May 26th, 2025
LCM of 14 and 21
The Least common multiple (LCM) is the smallest number that is divisible by the numbers 14 and 21. The LCM can be found using the listing multiples method, the prime factorization and/or division methods. LCM helps to solve problems with fractions and scenarios like scheduling or aligning repeating cycle of events.
What is the LCM of 14 and 21?
The LCM of 14 and 21 is the smallest positive integer, a multiple of both numbers. By finding the LCM, we can simplify the arithmetic operations with fractions to equate the denominators.
How to find the LCM of 14 and 21?
There are various methods to find the LCM, Listing method, prime factorization method and division method are explained below;
LCM of 14 and 21 using the Listing multiples method
To ascertain the LCM, list the multiples of the integers until a common multiple is found.
Steps:
1. Write down the multiples of each number:
Multiples of 14 = 14,28,42,…
Multiples of 21= 21,42,63…
2. Ascertain the smallest multiple from the listed multiples
The least common multiple of the numbers is 42.
LCM of 14 and 21 using the Prime Factorization
The prime factors of each number are written, and then the highest power of the prime factors is multiplied to get the LCM.
Steps:
1. Find the prime factors of the numbers:
Prime factorization of 14 = 2×7
Prime factorization of 21= 3×7
2. Take the highest power of each prime factor and multiply the ascertained factors.
— LCM = 42
LCM of 14 and 21 using the Division Method
The Division Method involves simultaneously dividing the numbers by their prime factors and multiplying the divisors to get the LCM.
Steps:
1. Write down the numbers in a row;
2. Divide the row of numbers by a prime number that is evenly divisible into at least one of the given numbers. Continue dividing the numbers until the last row of the results is ‘1’ and bring down the numbers not divisible by the previously chosen prime number.
3. The LCM of the numbers is the product of the prime numbers in the first column, i.e,
2×7×3 = 42
Common Mistakes and how to avoid them while finding the LCM of 14 and 21
Listed below are a few commonly made mistakes while attempting to ascertain the LCM of 14 and 21, make a note while practicing.
Mistake 1
Listing incorrect/overlooking multiples for the given numbers 14 and 21
This can be avoided by always double-checking the multiples of the numbers 14 and 21, and by not stopping too early. To elaborate, listing 14,28 as multiples of 14 and 21,42 as multiples of 21 and assuming 28 is the LCM.
LCM of 14 and 21 Examples
Problem 1
Ram goes to the office canteen every 14 days, and his boss goes every 21 days. After how many days will they meet on the same day again?
The LCM of 14 and 21 is 42.
Explanation
They will meet again on the same day in 42 days. The LCM of 14 and 21 is 42, which expresses the smallest common time interval between the digits.
Problem 2
Machine X stops for maintenance every 14 hours, while machine Y stops every 21 hours. In how long will the machines stop again?
The LCM of 14 and 21 is 42.
Explanation
The machines will stop every 42 hours. The LCM of 14 and 21 is 42, which expresses the smallest common time interval between the digits.
Problem 3
A store receives shipments of apples every 14 days and pineapples every 21 days. If both shipments arrive today, in how many days will both shipments arrive again on the same day?
The LCM of 14 and 21 is 42.
Explanation
Both the shipments will arrive together again in 42 days. The LCM of 14 and 21 is 42, which expresses the smallest common time interval between the digits.
Problem 4
Leo, and Will, have classroom clean-up duties. Emma is assigned to cleaning duties every 14 days and Jack every 21 days. If both are assigned clean-up today, when will they next be assigned on the same day?
The LCM of 14 and 21 is 42.
Explanation
Both of them will be assigned to clean up in 42 days. The LCM of 14 and 21 is 42, which expresses the smallest common time interval between the digits.
FAQ’s on LCM of 14 and 21
1.What is the relationship between the Greatest Common Divisor (GCD) and LCM of 14 and 21?
2.What is the LCM of algebraic expressions?
3.How do you find the LCM with different bases in an exponential equation?
4.What is the LCM formula using the HCF ?
5.How do you derive the LCM of two decimal numbers? Explain using 14.0 and 21.0.
6.How can children in India use numbers in everyday life to understand LCM of 14 and 21?
7.What are some fun ways kids in India can practice LCM of 14 and 21 with numbers?
8.What role do numbers and LCM of 14 and 21 play in helping children in India develop problem-solving skills?
9.How can families in India create number-rich environments to improve LCM of 14 and 21 skills?
Important glossaries on the LCM of 14 and 21
- Multiple: A product of a number and any integer.
- Prime Factor: A prime factor is a natural number, other than 1, whose only factors are 1 and itself.
- Prime Factorization: The process of breaking down a number into its prime factors.
- Co-prime numbers: A number is co-prime when the only positive integer that is a divisor of them both is 1.
- Greatest Common Divisor (GCD): The largest positive integer that divides each of two or more integers without leaving a remainder.
- Relatively Prime Numbers: Two numbers that have no common factors other than 1.
- Fraction: A number representing a part of a whole.
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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
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