LCM of 5 and 18

LCM of 5 and 18 is the smallest number among all common multiples of 5 and 18. The first few multiples of 5 and 18 are (5, 10, 15, 20, 25, . . . ) and (18, 36, 54, 72, 90, 108, . . . ) respectively. There are 3 commonly used methods to find LCM of 5 and 18 - by division method, by listing multiples, and by prime factorization.

Answer: LCM of 5 and 18 is 90.

Explanation:

The LCM of two non-zero integers, x(5) and y(18), is the smallest positive integer m(90) that is divisible by both x(5) and y(18) without any remainder.

Let's look at the different methods for finding the LCM of 5 and 18.

• By Division Method
• By Listing Multiples
• By Prime Factorization Method

LCM of 5 and 18 by Division Method

To calculate the LCM of 5 and 18 by the division method, we will divide the numbers(5, 18) by their prime factors (preferably common). The product of these divisors gives the LCM of 5 and 18.

• Step 1: Find the smallest prime number that is a factor of at least one of the numbers, 5 and 18. Write this prime number(2) on the left of the given numbers(5 and 18), separated as per the ladder arrangement.
• Step 2: If any of the given numbers (5, 18) is a multiple of 2, divide it by 2 and write the quotient below it. Bring down any number that is not divisible by the prime number.
• Step 3: Continue the steps until only 1s are left in the last row.

The LCM of 5 and 18 is the product of all prime numbers on the left, i.e. LCM(5, 18) by division method = 2 × 3 × 3 × 5 = 90.

LCM of 5 and 18 by Listing Multiples

To calculate the LCM of 5 and 18 by listing out the common multiples, we can follow the given below steps:

• Step 1: List a few multiples of 5 (5, 10, 15, 20, 25, . . . ) and 18 (18, 36, 54, 72, 90, 108, . . . . )
• Step 2: The common multiples from the multiples of 5 and 18 are 90, 180, . . .
• Step 3: The smallest common multiple of 5 and 18 is 90.

∴ The least common multiple of 5 and 18 = 90.

LCM of 5 and 18 by Prime Factorization

Prime factorization of 5 and 18 is (5) = 5¹ and (2 × 3 × 3) = 2¹ × 3² respectively. LCM of 5 and 18 can be obtained by multiplying prime factors raised to their respective highest power, i.e. 2¹ × 3² × 5¹ = 90.
Hence, the LCM of 5 and 18 by prime factorization is 90.

☛ Also Check:

• LCM of 20, 30 and 60 - 60
• LCM of 4, 7 and 8 - 56
• LCM of 4 and 14 - 28
• LCM of 8 and 64 - 64
• LCM of 28 and 42 - 84
• LCM of 15 and 45 - 45
• LCM of 12 and 16 - 48

FAQs on LCM of 5 and 18

What is the LCM of 5 and 18?

The LCM of 5 and 18 is 90. To find the least common multiple of 5 and 18, we need to find the multiples of 5 and 18 (multiples of 5 = 5, 10, 15, 20 . . . . 90; multiples of 18 = 18, 36, 54, 72 . . . . 90) and choose the smallest multiple that is exactly divisible by 5 and 18, i.e., 90.

If the LCM of 18 and 5 is 90, Find its GCF.

LCM(18, 5) × GCF(18, 5) = 18 × 5
Since the LCM of 18 and 5 = 90
⇒ 90 × GCF(18, 5) = 90
Therefore, the greatest common factor = 90/90 = 1.

What are the Methods to Find LCM of 5 and 18?

The commonly used methods to find the LCM of 5 and 18 are:

• Division Method
• Prime Factorization Method
• Listing Multiples

What is the Least Perfect Square Divisible by 5 and 18?

The least number divisible by 5 and 18 = LCM(5, 18)
LCM of 5 and 18 = 2 × 3 × 3 × 5 [Incomplete pair(s): 2, 5]
⇒ Least perfect square divisible by each 5 and 18 = LCM(5, 18) × 2 × 5 = 900 [Square root of 900 = √900 = ±30]
Therefore, 900 is the required number.

How to Find the LCM of 5 and 18 by Prime Factorization?

To find the LCM of 5 and 18 using prime factorization, we will find the prime factors, (5 = 5) and (18 = 2 × 3 × 3). LCM of 5 and 18 is the product of prime factors raised to their respective highest exponent among the numbers 5 and 18.
⇒ LCM of 5, 18 = 2¹ × 3² × 5¹ = 90.