GCF of 28 and 70 is the largest possible number that divides 28 and 70 exactly without any remainder. The factors of 28 and 70 are 1, 2, 4, 7, 14, 28 and 1, 2, 5, 7, 10, 14, 35, 70 respectively. There are 3 commonly used methods to find the GCF of 28 and 70 - long division, prime factorization, and Euclidean algorithm.

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1.GCF of 28 and 70
2.List of Methods
3.Solved Examples
4.FAQs

Answer: GCF of 28 and 70 is 14.

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Explanation:

The GCF of two non-zero integers, x(28) and y(70), is the greatest positive integer m(14) that divides both x(28) and y(70) without any remainder.


The methods to find the GCF of 28 and 70 are explained below.

Prime Factorization MethodListing Common FactorsLong Division Method

GCF of 28 and 70 by Prime Factorization

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Prime factorization of 28 and 70 is (2 × 2 × 7) and (2 × 5 × 7) respectively. As visible, 28 and 70 have common prime factors. Hence, the GCF of 28 and 70 is 2 × 7 = 14.

GCF of 28 and 70 by Listing Common Factors

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Factors of 28: 1, 2, 4, 7, 14, 28Factors of 70: 1, 2, 5, 7, 10, 14, 35, 70

There are 4 common factors of 28 and 70, that are 1, 2, 14, and 7. Therefore, the greatest common factor of 28 and 70 is 14.

GCF of 28 and 70 by Long Division

GCF of 28 and 70 is the divisor that we get when the remainder becomes 0 after doing long division repeatedly.

Step 2: Since the remainder ≠ 0, we will divide the divisor of step 1 (28) by the remainder (14).Step 3: Repeat this process until the remainder = 0.

The corresponding divisor (14) is the GCF of 28 and 70.

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GCF of 28 and 70 Examples


Example 1: For two numbers, GCF = 14 and LCM = 140. If one number is 28, find the other number.

Solution:

Given: GCF (y, 28) = 14 and LCM (y, 28) = 140∵ GCF × LCM = 28 × (y)⇒ y = (GCF × LCM)/28⇒ y = (14 × 140)/28⇒ y = 70Therefore, the other number is 70.


Example 2: Find the GCF of 28 and 70, if their LCM is 140.

Solution:

∵ LCM × GCF = 28 × 70⇒ GCF(28, 70) = (28 × 70)/140 = 14Therefore, the greatest common factor of 28 and 70 is 14.


Example 3: The product of two numbers is 1960. If their GCF is 14, what is their LCM?

Solution:

Given: GCF = 14 and product of numbers = 1960∵ LCM × GCF = product of numbers⇒ LCM = Product/GCF = 1960/14Therefore, the LCM is 140.


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FAQs on GCF of 28 and 70

What is the GCF of 28 and 70?

The GCF of 28 and 70 is 14. To calculate the greatest common factor (GCF) of 28 and 70, we need to factor each number (factors of 28 = 1, 2, 4, 7, 14, 28; factors of 70 = 1, 2, 5, 7, 10, 14, 35, 70) and choose the greatest factor that exactly divides both 28 and 70, i.e., 14.

What is the Relation Between LCM and GCF of 28, 70?

The following equation can be used to express the relation between Least Common Multiple (LCM) and GCF of 28 and 70, i.e. GCF × LCM = 28 × 70.

If the GCF of 70 and 28 is 14, Find its LCM.

GCF(70, 28) × LCM(70, 28) = 70 × 28Since the GCF of 70 and 28 = 14⇒ 14 × LCM(70, 28) = 1960Therefore, LCM = 140☛ Greatest Common Factor Calculator

How to Find the GCF of 28 and 70 by Long Division Method?

To find the GCF of 28, 70 using long division method, 70 is divided by 28. The corresponding divisor (14) when remainder equals 0 is taken as GCF.

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How to Find the GCF of 28 and 70 by Prime Factorization?

To find the GCF of 28 and 70, we will find the prime factorization of the given numbers, i.e. 28 = 2 × 2 × 7; 70 = 2 × 5 × 7.⇒ Since 2, 7 are common terms in the prime factorization of 28 and 70. Hence, GCF(28, 70) = 2 × 7 = 14☛ What are Prime Numbers?

What are the Methods to Find GCF of 28 and 70?

There are three commonly used methods to find the GCF of 28 and 70.