Download How_to_find_GCF_and_LCM_u sing_the_slide[1]

We call it the slide You may know it as upside down division or UDD
You can use the slide (UDD) for several things. You can use the slide for prime factorization, finding GCF,
finding LCM and for simplifying fractions.( We will show simplifying fractions later)
1. To use the slide for prime factorization, put your number into the UDD bracket, and
then choose a prime number that can divide your number without a remainder. Repeat
this process until you have a prime number at the bottom of your UDD. Point out to your
students that they can use the upside down division sign just like they would if it was
flipped over, and then use short hand division to find the dividends.
2
420
2
210
5
105
3
21
420 = 2x2x3x5x7
7
2.
Find the GCF of 36 and 48. Find the LCM of 36 and 48.
To use the slide to find GCF and LCM, it works the same as above.
1. Choose a prime number that can divide into both numbers without a remainder. For example 2 will
divide into 36 and 48 evenly. 2 will divide into 36, 18 times.
2. Place the number 18 under the 36.
3. Do the same with 48. It will divide into 48, 24 times. Place 24 under 48.
4. Now, find a prime number that will divide into 18 and 24.
5. Repeat this process until you can no longer divide both of your numbers by a prime number.
6. To get the GCF- Multiply the numbers on the side.
7. To get the LCM multiply the numbers on the side and at the bottom.
2
36
48
2
18
24
3
9
12
3
4
GCF = 2x2x3 = 12
2
36
48
2
18
24
3
9
12
3
4
LCM = 2x2x3x3x4 = 144 (notice the “L”)