1. § 1.3
Fractions

2. Numerators and Denominators
A quotient of two numbers is called a fraction.
The fraction represents the shaded part of the circle. 1 out of 4 pieces is shaded. is read “one-fourth.”
numerator
denominator

3. Simplifying Fractions
To simplify fractions we can simplify the numerator and the denominator. 2 5 10 =
factors
product
A fraction is said to be simplified or in lowest terms when the numerator and denominator have no factors in common other than 1.

4. Prime and Composite Numbers
A prime number is a natural number, other than 1, whose only factors are 1 and itself.
2, 3, 5, 7, 11, 13, 17, 19, 23, 29
The first 10 prime numbers
A natural number, other than 1, that is not a prime number is called a composite number. Every composite number can be written as a product of prime numbers

5. Product of Primes Example: Write the number 24 as a product of primes.
24 =  6
Write 24 as the product of any two whole numbers.
If the factors are not prime, they must be factored.
2  2
2  3
24 = 2  2  2  3
When all of the factors are prime, the number has been completely factored.

6. The Fundamental Principal of Fractions
If is a fraction and c is a nonzero real number, then
Example:
Write the fraction in lowest terms.

7. Multiplying Fractions
To multiply two fractions, multiply numerator times numerator to obtain the numerator of the product.
Multiply denominator times denominator to obtain the denominator of the product.
Multiplying Fractions

8. Multiplying Fractions
Example: Multiply.
Multiply numerators.
Multiply denominators.
Simplify the product by dividing the numerator and the denominator by any common factors.

9. Dividing Fractions
Two fractions are reciprocals of each other if their product is 1.
Dividing Fractions

10. Dividing Fractions
Example: Divide.

11. Fractions with the Same Denominator
To add or subtract fractions with the same denominator, combine numerators and place the sum or difference over the common denominator.
Adding and Subtracting Fractions with the Same Denominator

12. Equivalent Fractions
Equivalent fractions are fractions that represent the same quantity.
is shaded.
is shaded.
Equivalent fractions

13. Equivalent Fractions Example: Write as an equivalent fraction with a
denominator of 20.
Since 4 · 5 = 20, multiply the fraction by

14. Fractions without the Same Denominator
To add or subtract fractions without the same denominator, first write the fractions as equivalent fractions with a common denominator
The least common denominator (LCD) is the smallest number both denominators will divide evenly into.
Example:
LCD = 24

15. Fractions without the Same Denominator
Example:
LCD = 60