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102 LearnersLast updated on September 10, 2025
GCF of 18 and 50
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 schedule events. In this topic, we will learn about the GCF of 18 and 50.
What is the GCF of 18 and 50?
The greatest common factor of 18 and 50 is 2. 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 18 and 50?
To find the GCF of 18 and 50, a few methods are described below -
- Listing Factors
- Prime Factorization
- Long Division Method / by Euclidean Algorithm
GCF of 18 and 50 by Using Listing of Factors
Steps to find the GCF of 18 and 50 using the listing of factors
Step 1: Firstly, list the factors of each number Factors of 18 = 1, 2, 3, 6, 9, 18. Factors of 50 = 1, 2, 5, 10, 25, 50.
Step 2: Now, identify the common factors of them Common factors of 18 and 50: 1, 2.
Step 3: Choose the largest factor The largest factor that both numbers have is 2. The GCF of 18 and 50 is 2.
GCF of 18 and 50 Using Prime Factorization
To find the GCF of 18 and 50 using Prime Factorization Method, follow these steps:
Step 1: Find the prime factors of each number Prime Factors of 18: 18 = 2 x 3 x 3 = 2 x 3² Prime Factors of 50: 50 = 2 x 5 x 5 = 2 x 5²
Step 2: Now, identify the common prime factors The common prime factor is: 2
Step 3: Multiply the common prime factors 2 = 2. The Greatest Common Factor of 18 and 50 is 2.
GCF of 18 and 50 Using Division Method or Euclidean Algorithm Method
Find the GCF of 18 and 50 using the division method or Euclidean Algorithm Method. Follow these steps:
Step 1: First, divide the larger number by the smaller number Here, divide 50 by 18 50 ÷ 18 = 2 (quotient), The remainder is calculated as 50 − (18×2) = 14 The remainder is 14, not zero, so continue the process
Step 2: Now divide the previous divisor (18) by the previous remainder (14) Divide 18 by 14 18 ÷ 14 = 1 (quotient), remainder = 18 − (14×1) = 4
Step 3: Divide the previous divisor (14) by the remainder (4) 14 ÷ 4 = 3 (quotient), remainder = 14 − (4×3) = 2
Step 4: Divide the previous divisor (4) by the remainder (2) 4 ÷ 2 = 2 (quotient), remainder = 4 − (2×2) = 0
The remainder is zero, the divisor will become the GCF. The GCF of 18 and 50 is 2.
Common Mistakes and How to Avoid Them in GCF of 18 and 50
Finding GCF of 18 and 50 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 50, students may mention 15 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 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 18 and 50 Examples
Problem 1
A gardener has 18 rose bushes and 50 tulip bulbs. She wants to plant them in equal groups, with the largest number of plants in each group. How many plants will be in each group?
We should find GCF of 18 and 50 GCF of 18 and 50 2. There are 2 equal groups 18 ÷ 2 = 9 50 ÷ 2 = 25 There will be 2 groups, and each group gets 9 rose bushes and 25 tulip bulbs.
Explanation
As the GCF of 18 and 50 is 2, the gardener can make 2 groups. Now divide 18 and 50 by 2. Each group gets 9 rose bushes and 25 tulip bulbs.
Problem 2
A factory has 18 machines and 50 workers. They want to organize them into teams with the same number of machines and workers in each team, using the largest possible number of machines per team. How many machines will be in each team?
GCF of 18 and 50 2. So each team will have 2 machines.
Explanation
There are 18 machines and 50 workers. To find the total number of machines in each team, we should find the GCF of 18 and 50. There will be 2 machines in each team.
Problem 3
A chef has 18 eggs and 50 grams of butter. She wants to divide them into portions of equal size, using the largest possible size. What should be the size of each portion?
For calculating the largest equal size, we have to calculate the GCF of 18 and 50 The GCF of 18 and 50 2. The size of each portion is 2 units.
Explanation
For calculating the largest size of the portions first we need to calculate the GCF of 18 and 50 which is 2. The size of each portion will be 2 units.
Problem 4
A carpenter has two wooden planks, one 18 cm long and the other 50 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 18 and 50 2. The longest length of each piece is 2 cm.
Explanation
To find the longest length of each piece of the two wooden planks, 18 cm and 50 cm, respectively. We have to find the GCF of 18 and 50, which is 2 cm. The longest length of each piece is 2 cm.
Problem 5
If the GCF of 18 and ‘a’ is 2, and the LCM is 450. Find ‘a’.
The value of ‘a’ is 50.
Explanation
GCF x LCM = product of the numbers 2 × 450 = 18 × a 900 = 18a a = 900 ÷ 18 = 50
FAQs on the Greatest Common Factor of 18 and 50
1.What is the LCM of 18 and 50?
2.Is 18 divisible by 3?
3.What will be the GCF of any two prime numbers?
4.What is the prime factorization of 50?
5.Are 18 and 50 prime numbers?
Important Glossaries for GCF of 18 and 50
- Factors: Factors are numbers that divide the target number completely. For example, the factors of 18 are 1, 2, 3, 6, 9, and 18.
- 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 18 are 2 and 3.
- Remainder: The value left after division when the number cannot be divided evenly. For example, when 18 is divided by 5, the remainder is 3 and the quotient is 3.
- LCM: The smallest common multiple of two or more numbers is termed LCM. For example, the LCM of 18 and 50 is 450.
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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.
