Question

What is the greatest factor 10 and 20 have in common?

Answer 1

Hint: Here in this question, we have to find the greatest common factor [GCF] of the given two numbers. To find this first we have to list out the factors of each number among the factors of two numbers, the largest common number which is the factor of both numbers known as greatest common factor.

Complete step by step answer:
The GCF (Greatest Common Factor) of two or more numbers is the greatest number among all the common factors of the given numbers. The GCF of two natural numbers x and y is the largest possible number which divides both x and y. "Greatest Common Factor" is also known as Highest Common Divisor (HCD) or Highest Common Factor (HCF) or Greatest Common Divisor (GCD).
There are 3 methods for finding the greatest common factor of two numbers.
Listing Out Common Factors
Prime Factorization
Division Method
In the question, the given we have to find the greatest common factor of $$10$$ and $$20$$
Now, find GCF by Listing Out the Common Factors
In this method, we have to list out the factors of both the numbers i.e., $$10$$ and $$20$$
Factor of 10: $$\left\{ {1,\,2,\,5,\,10} \right\}$$
Factor of 20: $$\left\{ {1,\,2,4,\,5,\,10,20} \right\}$$
Now list out the common factors of $$10$$ and $$20$$: $$\left\{ {1,\,2,\,5,\,10} \right\}$$
Now, we have to choose the greatest number in the common factors of $$10$$ and $$20$$ which is $$10$$.
Hence, the greatest common factor of $$10$$ and $$20$$ is $$10$$.

Note:
We can also solve this question by two more methods i.e., prime factorization and division method. In prime factorisation we will write numbers in the form of prime factors and from there we will take common factors of both numbers to get the required result.