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GCF of 4 and 8

GCF of 4 and 8 is the largest possible number that divides 4 and 8 exactly without any remainder. The factors of 4 and 8 are 1, 2, 4 and 1, 2, 4, 8 respectively. There are 3 commonly used methods to find the GCF of 4 and 8 - prime factorization, long division, and Euclidean algorithm.

1.	GCF of 4 and 8
2.	List of Methods
3.	Solved Examples
4.	FAQs

What is GCF of 4 and 8?

Answer: GCF of 4 and 8 is 4.

Explanation:

The GCF of two non-zero integers, x(4) and y(8), is the greatest positive integer m(4) that divides both x(4) and y(8) without any remainder.

Methods to Find GCF of 4 and 8

Let's look at the different methods for finding the GCF of 4 and 8.

Prime Factorization Method
Using Euclid's Algorithm
Listing Common Factors

GCF of 4 and 8 by Prime Factorization

Prime factorization of 4 and 8 is (2 × 2) and (2 × 2 × 2) respectively. As visible, 4 and 8 have common prime factors. Hence, the GCF of 4 and 8 is 2 × 2 = 4.

GCF of 4 and 8 by Euclidean Algorithm

As per the Euclidean Algorithm, GCF(X, Y) = GCF(Y, X mod Y)
where X > Y and mod is the modulo operator.

Here X = 8 and Y = 4

GCF(8, 4) = GCF(4, 8 mod 4) = GCF(4, 0)
GCF(4, 0) = 4 (∵ GCF(X, 0) = |X|, where X ≠ 0)

Therefore, the value of GCF of 4 and 8 is 4.

GCF of 4 and 8 by Listing Common Factors

Factors of 4: 1, 2, 4
Factors of 8: 1, 2, 4, 8

There are 3 common factors of 4 and 8, that are 1, 2, and 4. Therefore, the greatest common factor of 4 and 8 is 4.

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GCF of 4 and 8 Examples

Example 1: Find the GCF of 4 and 8, if their LCM is 8.

Solution:

∵ LCM × GCF = 4 × 8
⇒ GCF(4, 8) = (4 × 8)/8 = 4
Therefore, the greatest common factor of 4 and 8 is 4.
Example 2: Find the greatest number that divides 4 and 8 exactly.

Solution:

The greatest number that divides 4 and 8 exactly is their greatest common factor, i.e. GCF of 4 and 8.
⇒ Factors of 4 and 8:
- Factors of 4 = 1, 2, 4
- Factors of 8 = 1, 2, 4, 8
Therefore, the GCF of 4 and 8 is 4.
Example 3: For two numbers, GCF = 4 and LCM = 8. If one number is 4, find the other number.

Solution:

Given: GCF (y, 4) = 4 and LCM (y, 4) = 8
∵ GCF × LCM = 4 × (y)
⇒ y = (GCF × LCM)/4
⇒ y = (4 × 8)/4
⇒ y = 8
Therefore, the other number is 8.

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FAQs on GCF of 4 and 8

What is the GCF of 4 and 8?

The GCF of 4 and 8 is 4. To calculate the greatest common factor of 4 and 8, we need to factor each number (factors of 4 = 1, 2, 4; factors of 8 = 1, 2, 4, 8) and choose the greatest factor that exactly divides both 4 and 8, i.e., 4.

How to Find the GCF of 4 and 8 by Long Division Method?

To find the GCF of 4, 8 using long division method, 8 is divided by 4. The corresponding divisor (4) when remainder equals 0 is taken as GCF.

If the GCF of 8 and 4 is 4, Find its LCM.

GCF(8, 4) × LCM(8, 4) = 8 × 4
Since the GCF of 8 and 4 = 4
⇒ 4 × LCM(8, 4) = 32
Therefore, LCM = 8
☛ Greatest Common Factor Calculator

What are the Methods to Find GCF of 4 and 8?

There are three commonly used methods to find the GCF of 4 and 8.

By Prime Factorization
By Long Division
By Euclidean Algorithm

What is the Relation Between LCM and GCF of 4, 8?

The following equation can be used to express the relation between Least Common Multiple and GCF of 4 and 8, i.e. GCF × LCM = 4 × 8.

How to Find the GCF of 4 and 8 by Prime Factorization?

To find the GCF of 4 and 8, we will find the prime factorization of the given numbers, i.e. 4 = 2 × 2; 8 = 2 × 2 × 2.
⇒ Since 2, 2 are common terms in the prime factorization of 4 and 8. Hence, GCF(4, 8) = 2 × 2 = 4
☛ What is a Prime Number?

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