1. Adding and Subtracting Like Fractions, Least Common Denominator,
Section 4.4
Adding and Subtracting Like Fractions,
Least Common Denominator,
and Equivalent Fractions

2. Like Fractions
Like Fractions are multiple fractions with the same (exact) denominator.
Given the fractions below group the like fractions.

3. Adding Like Fraction
If a, b, and c are numbers and b is not equal to zero

5. Subtracting Like Fraction
If a, b, and c are numbers and b is not equal to zero

7. Lease Common Denominator
Least Common Denominator (LCD) is the smallest positive number divisible by all the denominators in the list.

8. LCD Methods
Multiples
Prime Factorization

9. Finding LCD by Multiples
Steps
List the multiples of each denominator
Find the same multiples in each list
The smallest multiple is the LCD

10. Finding LCD by Multiples
Find the LCD for LCD = 30

11. Example
Find the LCD

12. Example
Find the LCD

13. Finding LCD by Prime Factorization
Steps
Write each denominator in prime factorization.
Compare like prime numbers
Underline the group with the largest amount
If the amounts are equal underline one group
Multiply all underlined numbers together

14. Finding LCD by Prime Factorization
Find the LCD for 6 = 2 * 3 10 = 2 * 5 LCD = 2 * 3 * 5 = 30

15. Example
Find the LCD

16. Example
Find the LCD

17. Equivalent Fractions
Equivalent Fractions are two or more fractions that have the same value even if they look different.

18. Equivalent Fraction
To write an equivalent fraction Where a, b, and c are nonzero numbers

19. Example
Fill in the missing part to create an equivalent fraction

20. Example
Fill in the missing part to create an equivalent fraction

21. Example
Fill in the missing part to create an equivalent fraction

22. Example
Fill in the missing part to create an equivalent fraction