Answer:
1. 10 and 20
Solutions:
Finding the GCF
We must list first their factors.
10 = 1, 2, 5, and 10
20 = 1, 2, 4, 5, 10, and 20
Then, seek for the highest number that is common to both numbers. We can see that 10 is the highest number, so 10 is our GCF.
Finding the LCM
List first their multiples.
10 = 10, 20, 30, 40, 50
20 = 20, 40, 60, 80, 100
Then, seek for the lowest number that is common to both numbers. We can see that 20 is the lowest number, so 20 is our LCM.
GCF: 10
LCM: 20
2. 4 and 12
Solutions:
Finding the GCF
We must list first their factors.
4 = 1, 2, 4
12 = 1, 2, 3, 4, 6, 12
Then, seek for the highest number that is common to both numbers. We can see that 4 is the highest number, so 4 is our GCF.
Finding the LCM
List first their multiples.
4 = 4, 8, 12, 16, 20, 24
12 = 12, 24, 36, 48, 60
Then, seek for the lowest number that is common to both numbers. We can see that 12 is the lowest number, so 12 is our LCM.
GCF: 4
LCM: 12
3. 10 and 15
Solutions:
Finding the GCF
We must list first their factors.
10 = 1, 2, 5, and 10
15 = 1, 2, 3, 5, 15
Then, seek for the highest number that is common to both numbers. We can see that 5 is the highest number, so 5 is our GCF.
Finding the LCM
List first their multiples.
10 = 10, 20, 30, 40, 50
15 = 15, 30, 45, 60, 75
Then, seek for the lowest number that is common to both numbers. We can see that 30 is the lowest number, so 30 is our LCM.
GCF: 5
LCM: 30
4. 6 and 24
Solutions:
Finding the GCF
We must list first their factors.
6 = 1, 2, 3, 6
24 = 1, 2, 4, 6, 12, 24
Then, seek for the highest number that is common to both numbers. We can see that 6 is the highest number, so 6 is our GCF.
Finding the LCM
List first their multiples.
6 = 6, 12, 18, 24, 30, 36
24 = 24, 48, 72
Then, seek for the lowest number that is common to both numbers. We can see that 24 is the lowest number, so 24 is our LCM.
GCF: 6
LCM: 24
5. 25 and 30
Solutions:
Finding the GCF
We must list first their factors.
25 = 1, 5, 25
30 = 1, 2, 3, 5, 6, 10, 15, 30
Then, seek for the highest number that is common to both numbers. We can see that 5 is the highest number, so 5 is our GCF.
Finding the LCM
List first their multiples.
25 = 25, 50, 75, 100, 125, 150
30 = 30, 60, 90, 120, 150
Then, seek for the lowest number that is common to both numbers. We can see that 150 is the lowest number, so 150 is our LCM.
GCF: 5
LCM: 150
