2. + Fractions: Addition & Subtraction Algebra Seminar 2012-2013

3. Two Fractions can be combined easily when they have a common denominator.

4. + Def. Common Denominator- A number that all of the denominators divide into evenly.

5. + Common Denominator (similar to LCM) A number all original denominators divide into evenly 12 is a common denominator because 3 and 4 both divide 12 evenly.

6. Least Common Denominator (same as LCM) To find the least common denominator * Write the times table list for each denominator * The smallest number that is in all rows is the least common denominator

7. + Least Common Denominator To find the least common denominator Write the times table list for each denominator The smallest number that is in all rows is the least common denominator

8. + The least common denominator is: 24!!!

9. + Practice - Find the common denominator for these fractions. 2 / 3 + 3 / 5 ¾ + 7 / 12 2 / 5 + 3 / 8 + 7 / 10

10. What if the denominators do NOT match? If the denominators do not match, you must find the LCM to change them.

11. + Subtracting Fractions

12. + Subtraction – the process is the same but you will subtract the numerators instead of adding them. Squirt reminds you to: 1) Get a Common Denominator 2) Subtract

13. + Extra Practice

14. + Subtraction What is different about this problem? We have a mixed number! Lets change them to improper fractions!

15. Subtraction Practice