Question

How do you find the GCF of $15$ and $25?$

Answer 1

Hint: Whenever they ask to find the greatest common factor of any two numbers, first we need to find the factors of those numbers. Factors of a number is nothing but the number that divides the given number without a remainder. Now, first find the factors of $15$ and $25$ , then the common highest factor will be the required answer for the question.

Complete step-by-step answer:
In the question they have asked us to find the greatest common factor of $15$ and $25$ . So first we need to find the factors of the number $15$ and the factor of $25$ separately.
Now we find the factors of $15$ .
Factors are nothing but the numbers which divide the given number without giving any remainder or with zero as the remainder.
Therefore we have,
$3 \times 5 = 15$
From this we can say that $1,3$ and $5$ are factors of $15$ , one being the factor of all the numbers but it is not the highest factor so it is not necessary to mention. If we mention also not a problem.
Now we find the factors of $25$ .
$5 \times 5 = 25$ Therefore the factors of $25$ is $1,5$ .
Now compare the factors of $15$ and $25$.
When we compare the factors of both we notice that the common factors are $1$ and $5$ .
They have asked for the greatest common factor, hence when we look at common factors that are $1$ and $5$ , we can say that the highest or greatest common factor is $5$ .

Note: If they ask for the greatest common factor then you have to find factors of given numbers. If factors are the same in both the given numbers then you can look for the highest common factor, so try to find factors properly, if not it may lead to wrong answers.