Answers − Highest Common Factor or Greatest Common Factor

1.	What is the highest common factor of 8 and 12?
	The factors of 8 are 1, 2, 4 and 8
	The factors of 12 are 1, 2, 3, 4, 6 and 12
	So the highest common factor is 4

2.	What is the highest common factor of 16 and 24?
	The factors of 16 are 1, 2, 4, 8 and 16
	The factors of 24 are 1, 2, 3, 4, 6, 8, 12 and 24
	So the highest common factor is 8

3.	What is the highest common factor of 28 and 42?
	The factors of 28 are 1, 2, 4, 6, 14 and 28
	The factors of 42 are 1, 2, 3, 6, 7, 14, 21 and 42
	So the highest common factor is 14

4.	What is the highest common factor of 8 and 24?
	The factors of 8 are 1, 2, 4 and 8
	The factors of 24 are 1, 2, 3, 4, 6, 8, 12 and 24
	So the highest common factor is 8

5.	What is the highest common factor of 15 and 18?
	The factors of 15 are 1, 3, 5 and 15
	The factors of 18 are 1, 2, 3, 6, 9 and 18
	So the highest common factor is 3

6.	What is the highest common factor of 20 and 32?
	The factors of 20 are 1, 2, 4, 5, 10 and 20
	The factors of 32 are 1, 2, 4, 8, 16 and 32
	So the highest common factor is 4

7.	What is the highest common factor of 18 and 30?
	The factors of 18 are 1, 2, 3, 6, 9 and 18
	The factors of 30 are 1, 2, 3, 5, 6, 10, 15 and 30
	So the highest common factor is 6

8.	What is the highest common factor of 15, 24 and 30?
	The factors of 15 are 1, 3, 5 and 15
	The factors of 24 are 1, 2, 3, 4, 6, 8, 12 and 24
	The factors of 30 are 1, 2, 3, 5, 6, 10, 15 and 30
	So the highest common factor is 3

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