LCM of 42 and 63

The common multiples of 42 and 63 is 126.  Here, we will learn about the LCM of 2 numbers. Children learn about LCM at younger ages. Here, we will discuss the methods used for finding out LCM.
 

Out of many methods, the prime factorization method is widely used for its easy approach. Here, we will learn about other methods as well. A few commonly used methods are as follows - 

1. Listing Of Multiples
2. Prime Factorization
3. Division Method
    

Listing multiples can be a tedious method for finding the LCM. Here, the listing of multiples for all these 2 numbers is noted - 

• Multiples of 42 are  42, 84, 126, 168
• Multiples of 63 are 63, 126, 189 

Then we can see that out of 42 and 63, 126 is the smallest common number that is present in them. So we see that 126 is the LCM of 42 and 63. 
 

The product of the highest power of prime factors of 42 and 63 is the LCM of these numbers. So let us look at it step by step to understand it better.

Breaking the given numbers into their prime factors.

Prime factorization of 42 = 2 × 3 × 7
Prime factorization of 63 = 3²  × 7

Multiplying the highest power of prime factors: 2¹ × 3² × 7¹ →  2 × 9 × 7 = 126

LCM of 42 and 63 is 126.
 

In this method, we will be dividing the given numbers with the common prime factors until all numbers are reduced to 1. Let us look at this step by step and make it easy for the children to learn it.

Step 1: Arrange the number in a sequence, divisors, and the numbers are on the left and right sides respectively.

Step 2: For finding the divisor, it is always the smallest common prime factor. Here, the smallest common prime factor is 2. Dividing 42 and 63 by 2. The result is 21 and 63. 

Step 3: As 21 and 63 are divisible by 3, the divisor is 3. Dividing 21 and 63 by 3. Now the result is 7 and 21.

Step 4: Continue dividing the numbers with the smallest prime number until all numbers are reduced to 1.

The divisors are 2, 3, 3, 7. LCM of 42 and 63 is the product of divisors.

Hence, the LCM of (42 and 63) = 2 × 3  × 3 × 7 = 126
 

• Factor: A number that will divide two or more numbers, leaving no remainder. For 18 and 24 we have 6 as a common factor, it means both 18 and 24 can be divisible by 6.

• Prime Factorization: When a number can be represented as the factors of prime numbers, it is called prime factorization. The prime factorization of 18 for example is 2×3×3.

• Greatest Common Factor (GCF): GCF is the greatest factor that is common in the given numbers. For example, the GCF of 5, 10, and 15 is 5. Because the common factors of 5 and 10 are 1 and 5.

• Division Method: In the division method, the numbers are divided by the smallest common prime factor till the numbers are reduced to 1.