112 LearnersLast updated on August 12, 2025
GCF of 42 and 49
The GCF is the largest number that can divide two or more numbers without leaving any remainder. GCF is used to share the items equally, to group or arrange items, and to schedule events. In this topic, we will learn about the GCF of 42 and 49.
What is the GCF of 42 and 49?
The greatest common factor of 42 and 49 is 7. The largest divisor of two or more numbers is called the GCF of the number.
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 42 and 49?
To find the GCF of 42 and 49, a few methods are described below -
- Listing Factors
- Prime Factorization
- Long Division Method / by Euclidean Algorithm
GCF of 42 and 49 by Using Listing of Factors
Steps to find the GCF of 42 and 49 using the listing of factors:
Step 1: Firstly, list the factors of each number. Factors of 42 = 1, 2, 3, 6, 7, 14, 21, 42. Factors of 49 = 1, 7, 49.
Step 2: Now, identify the common factors of them. Common factors of 42 and 49: 1, 7.
Step 3: Choose the largest factor. The largest factor that both numbers have is 7. The GCF of 42 and 49 is 7.
GCF of 42 and 49 Using Prime Factorization
To find the GCF of 42 and 49 using the Prime Factorization Method, follow these steps:
Step 1: Find the prime factors of each number. Prime Factors of 42: 42 = 2 x 3 x 7. Prime Factors of 49: 49 = 7 x 7.
Step 2: Now, identify the common prime factors. The common prime factor is: 7.
Step 3: Multiply the common prime factors. The Greatest Common Factor of 42 and 49 is 7.
GCF of 42 and 49 Using Division Method or Euclidean Algorithm Method
Find the GCF of 42 and 49 using the division method or Euclidean Algorithm Method. Follow these steps:
Step 1: First, divide the larger number by the smaller number. Here, divide 49 by 42. 49 ÷ 42 = 1 (quotient), The remainder is calculated as 49 − (42×1) = 7. The remainder is 7, not zero, so continue the process.
Step 2: Now divide the previous divisor (42) by the previous remainder (7). Divide 42 by 7. 42 ÷ 7 = 6 (quotient), remainder = 42 − (7×6) = 0. The remainder is zero, the divisor will become the GCF
The GCF of 42 and 49 is 7.
Common Mistakes and How to Avoid Them in GCF of 42 and 49
Finding the GCF of 42 and 49 looks simple, but students often make mistakes while calculating the GCF. Here are some common mistakes to be avoided by the students.
Mistake 1
Listing Incorrect Factors
Students may sometimes list incorrect factors. For example, while listing factors of 42, students may mention 8, which is incorrect. To avoid this, students should carefully divide the number and list the factors correctly.
Mistake 2
Choosing the Wrong Common Factor
Students may sometimes select the smallest common factor instead of the largest one. To avoid this confusion, students should list all the common factors and find the greatest one.
Mistake 3
Forgetting to Include 1 as a Factor
Sometimes students may forget 1 as a common factor of the numbers. However, it does not affect the GCF, but it tells about the incomplete understanding of the factors. Students should include 1 as a factor.
Mistake 4
Using Multiples Instead of Factors
Students confuse between factors and multiples. In that confusion, sometimes they may write multiples instead of factors. To avoid this confusion, students should know the definitions of multiples and factors clearly.
Mistake 5
Assuming GCF is Always an Even Number
Students may assume that the GCF of two numbers will always be an even number. But it's not true that a GCF can also be an odd number. To avoid this, students should focus on common factors rather than focusing on even and odd numbers.
Greatest Common Factor of 42 and 49 Examples
Problem 1
A gardener has 42 tulip bulbs and 49 daffodil bulbs. She wants to plant them in equal groups with the largest number of bulbs in each group. How many bulbs will be in each group?
We should find the GCF of 42 and 49. GCF of 42 and 49 is 7. There are 7 equal groups. 42 ÷ 7 = 6 49 ÷ 7 = 7 There will be 7 groups, and each group gets 6 tulip bulbs and 7 daffodil bulbs.
Explanation
As the GCF of 42 and 49 is 7, the gardener can make 7 groups. Now divide 42 and 49 by 7. Each group gets 6 tulip bulbs and 7 daffodil bulbs.
Problem 2
A chef has 42 chocolate bars and 49 vanilla bars. He wants to arrange them on plates with the same number of bars on each plate, using the largest possible number of bars per plate. How many bars will be on each plate?
GCF of 42 and 49 is 7. So each plate will have 7 bars.
Explanation
There are 42 chocolate bars and 49 vanilla bars. To find the total number of bars on each plate, we should find the GCF of 42 and 49. There will be 7 bars on each plate.
Problem 3
A farmer has 42 meters of fencing for the chicken coop and 49 meters for the goat pen. He wants to cut both pieces into sections of equal length, using the longest possible length. What should be the length of each section?
For calculating the longest equal length, we have to calculate the GCF of 42 and 49. The GCF of 42 and 49 is 7. The fencing section is 7 meters long.
Explanation
For calculating the longest length of the fencing, first, we need to calculate the GCF of 42 and 49, which is 7. The length of each section of the fencing will be 7 meters.
Problem 4
A carpenter has two wooden planks, one 42 cm long and the other 49 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?
The carpenter needs the longest piece of wood. GCF of 42 and 49 is 7. The longest length of each piece is 7 cm.
Explanation
To find the longest length of each piece of the two wooden planks, 42 cm and 49 cm, respectively, we have to find the GCF of 42 and 49, which is 7 cm. The longest length of each piece is 7 cm.
Problem 5
If the GCF of 42 and ‘a’ is 7, and the LCM is 294, find ‘a’.
The value of ‘a’ is 49.
Explanation
GCF x LCM = product of the numbers
7 × 294 = 42 × a
2058 = 42a
a = 2058 ÷ 42 = 49
FAQs on the Greatest Common Factor of 42 and 49
1.What is the LCM of 42 and 49?
2.Is 42 divisible by 2?
3.What will be the GCF of any two prime numbers?
4.What is the prime factorization of 49?
5.Are 42 and 49 prime numbers?
6.How can children in United States use numbers in everyday life to understand GCF of 42 and 49?
7.What are some fun ways kids in United States can practice GCF of 42 and 49 with numbers?
8.What role do numbers and GCF of 42 and 49 play in helping children in United States develop problem-solving skills?
9.How can families in United States create number-rich environments to improve GCF of 42 and 49 skills?
Important Glossaries for GCF of 42 and 49
- Factors: Factors are numbers that divide the target number completely. For example, the factors of 42 are 1, 2, 3, 6, 7, 14, 21, and 42.
- Multiple: Multiples are the products we get by multiplying a given number by another. For example, the multiples of 7 are 7, 14, 21, 28, 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 factor of 49 is 7.
- Remainder: The value left after division when the number cannot be divided evenly. For example, when 49 is divided by 42, the remainder is 7 and the quotient is 1.
- LCM: The smallest common multiple of two or more numbers is termed LCM. For example, the LCM of 42 and 49 is 294.
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.
