Question

Find all the common factors of 9 and 15.
A) 1, 3
B) 1, 3, 9
C) 1, 3, 5, 9

Answer 1

A common factor is a whole number which is a factor of two or more numbers.

`factors \: of \: 9 = 1 * 3 * 3`

`factors \: of \: 15 = 1 * 3 * 5`

since both of the numbers have only 1 and 3 in common.

therefore ,

Option A is correct.

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Additional information

★ The highest common factor (HCF) is the greatest factor that will divide into two or more numbers.

★ The lowest common multiple (LCM) is the smallest multiple that is common to two or more numbers.

hope helpful :D