Least Common Multiple of 4 and 5

Least common multiple or lowest common denominator (LCD) can be calculated in three ways;

• Least Common Multiple of 4 and 5 by Prime method
• Least Common Multiple of 4 and 5 with GCF Formula

Least common multiple can be found by multiplying the highest exponent prime factors of 4 and 5. First we will calculate the prime factors of 4 and 5.

Prime Factorization of 4

Prime factors of 4 are 2. Prime factorization of 4 in exponential form is:

4 = 2²

Prime Factorization of 5

Prime factors of 5 are 5. Prime factorization of 5 in exponential form is:

5 = 5¹

Now multiplying the highest exponent prime factors to calculate the LCM of 4 and 5.

LCM(4,5) = 2²×5¹
LCM(4,5) = 20

Factors of 4

List of positive integer factors of 4 that divides 4 without a remainder.

1, 2, 4

Factors of 5

List of positive integer factors of 5 that divides 5 without a remainder.

1, 5

The formula of LCM is LCM(a,b) = ( a × b) / GCF(a,b).
We need to calculate greatest common factor 4 and 5, than apply into the LCM equation.

GCF(4,5) = 1
LCM(4,5) = ( 4 × 5) / 1
LCM(4,5) = 20 / 1
LCM(4,5) = 20

(i) The LCM of 5 and 4 is associative

LCM of 4 and 5 = LCM of 5 and 4

1. What is the LCM of 4 and 5?

Answer: LCM of 4 and 5 is 20.

2. What are the Factors of 4?

Answer: Factors of 4 are 1, 2, 4. There are 3 integers that are factors of 4. The greatest factor of 4 is 4.

3. What are the Factors of 5?

Answer: Factors of 5 are 1, 5. There are 2 integers that are factors of 5. The greatest factor of 5 is 5.

4. How to Find the LCM of 4 and 5?

Answer:

Least Common Multiple of 4 and 5 = 20

Step 1: Find the prime factorization of 4

4 = 2 x 2

Step 2: Find the prime factorization of 5

5 = 5

Step 3: Multiply each factor the greater number of times it occurs in steps i) or ii) above to find the lcm:

LCM = 20 = 2 x 2 x 5

Step 4: Therefore, the least common multiple of 4 and 5 is 20.