Question

Find the common factors of 15 and 25.

Answer 1

Hint: Here, we will first list the prime factor of each number and list the number which is common in both the prime factor list. Then multiply each factor and if there are no common prime factors, then the common factor of the two numbers will be 1.

Complete step by step answer:

Consider, the two numbers, 15 and 25

List the prime factors of 15:

Prime factor of $15= 5 \times 3 \times 1$

List the prime factors of 25:

Prime factor of $25= 5 \times 5 \times 1$

Therefore, there are 1 and 5 which are common in both the lists.

Hence, The common factors of 15 and 25 are 5 and 1.

Note: In the above solution, you must be thinking about the prime number and difference between factors and common factors. “Prime Numbers” are the numbers that are greater than 1 and that have only two factors 1 and themselves.

Examples of prime numbers are 3,5,7,9 etc.

“Factors of N” are defined as the numbers which can be multiplied together to obtain another number N. Whereas common factors are determined between two or more numbers, when we find the factors of two or more numbers, and then some factors are obtained to be same or common in both the lists.