GCF of 6 and 45
2026-02-28 10:01 Diff
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Last updated on September 24, 2025

The GCF is the largest number that can divide two or more numbers without leaving any remainder. GCF is used to share items equally, to group or arrange items, and schedule events. In this topic, we will learn about the GCF of 6 and 45.

What is the GCF of 6 and 45?

The greatest common factor of 6 and 45 is 3. The largest divisor of two or more numbers is called the GCF of the numbers. If two numbers are co-prime, they have no common factors other than 1, so their GCF is 1.

The GCF of two numbers cannot be negative because divisors are always positive.

How to find the GCF of 6 and 45?

To find the GCF of 6 and 45, a few methods are described below 

  • Listing Factors
     
  • Prime Factorization
     
  • Long Division Method / by Euclidean Algorithm

GCF of 6 and 45 by Using Listing of Factors

Steps to find the GCF of 6 and 45 using the listing of factors:

Step 1: Firstly, list the factors of each number

Factors of 6 = 1, 2, 3, 6.

Factors of 45 = 1, 3, 5, 9, 15, 45.

Step 2: Now, identify the common factors of them Common factors of 6 and 45: 1, 3.

Step 3: Choose the largest factor The largest factor that both numbers have is 3.

The GCF of 6 and 45 is 3.

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GCF of 6 and 45 Using Prime Factorization

To find the GCF of 6 and 45 using the Prime Factorization Method, follow these steps:

Step 1: Find the prime factors of each number

Prime Factors of 6: 6 = 2 x 3

Prime Factors of 45: 45 = 3 x 3 x 5

Step 2: Now, identify the common prime factors

The common prime factor is 3.

Step 3: Multiply the common prime factors 3 = 3

The Greatest Common Factor of 6 and 45 is 3.

GCF of 6 and 45 Using Division Method or Euclidean Algorithm Method

Find the GCF of 6 and 45 using the division method or Euclidean Algorithm Method. Follow these steps:

Step 1: First, divide the larger number by the smaller number

Here, divide 45 by 6 45 ÷ 6 = 7 (quotient),

The remainder is calculated as 45 − (6×7) = 3

The remainder is 3, not zero, so continue the process

Step 2: Now divide the previous divisor (6) by the previous remainder (3)

Divide 6 by 3 6 ÷ 3 = 2 (quotient), remainder = 6 − (3×2) = 0

The remainder is zero, the divisor will become the GCF.

The GCF of 6 and 45 is 3.

Common Mistakes and How to Avoid Them in GCF of 6 and 45

Finding the GCF of 6 and 45 looks simple, but students often make mistakes while calculating the GCF. Here are some common mistakes to be avoided by the students.

Problem 1

A teacher has 6 apples and 45 oranges. She wants to group them into equal sets, with the largest number of items in each group. How many items will be in each group?

Okay, lets begin

We should find the GCF of 6 and 45 GCF of 6 and 45 3 = 3.

There are 3 equal groups 6 ÷ 3 = 2 45 ÷ 3 = 15

There will be 3 groups, and each group gets 2 apples and 15 oranges.

Explanation

As the GCF of 6 and 45 is 3, the teacher can make 3 groups.

Now divide 6 and 45 by 3.

Each group gets 2 apples and 15 oranges.

Well explained 👍

Problem 2

A school has 6 red flags and 45 blue flags. They want to arrange them in rows with the same number of flags in each row, using the largest possible number of flags per row. How many flags will be in each row?

Okay, lets begin

GCF of 6 and 45 3 = 3.

So each row will have 3 flags.

Explanation

There are 6 red and 45 blue flags.

To find the total number of flags in each row, we should find the GCF of 6 and 45.

There will be 3 flags in each row.

Well explained 👍

Problem 3

A tailor has 6 meters of red cloth and 45 meters of blue cloth. She wants to cut both cloths into pieces of equal length, using the longest possible length. What should be the length of each piece?

Okay, lets begin

For calculating the longest equal length, we have to calculate the GCF of 6 and 45

The GCF of 6 and 45 3 = 3.

The cloth is 3 meters long.

Explanation

For calculating the longest length of the cloth, first we need to calculate the GCF of 6 and 45, which is 3.

The length of each piece of the cloth will be 3 meters.

Well explained 👍

Problem 4

A carpenter has two wooden planks, one 6 cm long and the other 45 cm long. He wants to cut them into the longest possible equal pieces, without any wood left over. What should be the length of each piece?

Okay, lets begin

The carpenter needs the longest piece of wood GCF of 6 and 45 3 = 3.

The longest length of each piece is 3 cm.

Explanation

To find the longest length of each piece of the two wooden planks, 6 cm and 45 cm, respectively, we have to find the GCF of 6 and 45, which is 3 cm.

The longest length of each piece is 3 cm.

Well explained 👍

Problem 5

If the GCF of 6 and ‘a’ is 3, and the LCM is 90, find ‘a’.

Okay, lets begin

The value of ‘a’ is 45.

Explanation

GCF x LCM = product of the numbers

3 × 90 = 6 × a

270 = 6a

a = 270 ÷ 6 = 45

Well explained 👍

FAQs on the Greatest Common Factor of 6 and 45

1.What is the LCM of 6 and 45?

The LCM of 6 and 45 is 90.

2.Is 6 divisible by 2?

Yes, 6 is divisible by 2 because it is an even number.

3.What will be the GCF of any two prime numbers?

The common factor of prime numbers is 1 and the number itself. Since 1 is the only common factor of any two prime numbers, it is said to be the GCF of any two prime numbers.

4.What is the prime factorization of 45?

The prime factorization of 45 is 3 x 3 x 5.

5.Are 6 and 45 prime numbers?

No, 6 and 45 are not prime numbers because both of them have more than two factors.

Important Glossaries for GCF of 6 and 45

  • Factors: Factors are numbers that divide the target number completely. For example, the factors of 6 are 1, 2, 3, and 6.
  • Multiple: Multiples are the products we get by multiplying a given number by another. For example, the multiples of 5 are 5, 10, 15, 20, and so on.
  • Prime Factors: These are the factors of a number that are prime numbers and divide the given number completely. For example, the prime factors of 45 are 3 and 5.
  • Remainder: The value left after division when the number cannot be divided evenly. For example, when 10 is divided by 3, the remainder is 1 and the quotient is 3.
  • LCM: The smallest common multiple of two or more numbers is termed LCM. For example, the LCM of 6 and 45 is 90.
  • GCF: The largest factor that commonly divides two or more numbers. For example, the GCF of 6 and 45 is 3, as it is their largest common factor that divides the numbers completely.

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Hiralee Lalitkumar Makwana

About the Author

Hiralee Lalitkumar Makwana has almost two years of teaching experience. She is a number ninja as she loves numbers. Her interest in numbers can be seen in the way she cracks math puzzles and hidden patterns.

Fun Fact

: She loves to read number jokes and games.