4.1 & 4.2

4.1 & 4.2 Review!

Friday 10/16

Multiplying Fractions

• Step 1: Combine 2 fractions into one fraction

• Example:  $\frac{1}{2}\times\frac{2}{3}\rightarrow\ \frac{1\times2}{2\times3}$  

Multiplying Fractions

• Step 2: Multiply numerator and denominator

• Example: $\frac{1\times2}{2\times3}\rightarrow\ \frac{2}{6}$  

  
  

Multiplying Fractions

• Step 3: Simplify (if you can)

• Example: $\frac{2\div2}{6\div2}\rightarrow\ \frac{1}{3}$ 

• *REMEMBER: Whatever you do to the numerator, you have to do to the denominator

Open Ended

You try!

 $\frac{3}{4}\times\frac{2}{5}=?$  

Open Ended

You try!

 $\frac{4}{8}\times\frac{2}{3}=?$  

Multiplying whole numbers and fractions

• Step 1: Change the whole number into a fraction

• Example:  $4\times\frac{1}{3}\rightarrow\ \frac{4}{1}\times\frac{1}{3}$  

Multiplying whole numbers and fractions

• Step 2: Multiply the two fractions

• Example:   $\frac{4}{1}\times\frac{1}{3}\rightarrow\ \frac{4\times1}{1\times3}\rightarrow\ \frac{4}{3}$  

  
  

Multiplying whole numbers and fractions

• Step 3: Simplify (if you can)

• Example:   $\frac{4}{3}\rightarrow\ 1\frac{1}{3}$  

  
  

Open Ended

You try!

 $3\times\frac{2}{5}$  

Open Ended

You try!

 $5\times\frac{4}{6}$  

Adding fractions

• Step 1: Find common denominators (LCM)

• Example:  $\frac{1}{2}+\frac{3}{4}$  the denominators (2 and 4) have a LCM of 8

Adding fractions

• Step 2: Change the fractions so that they have a common denominator

• Example:  $\frac{1}{2}+\frac{3}{4}\rightarrow\ \frac{4}{8}+\frac{6}{8}$  

Adding Fractions

• Step 3: Add your numerators, keep your denominator the same

• Example:   $\frac{4}{8}+\frac{6}{8}=\frac{10}{8}$  

  
  

Adding Fractions

• Step 4: Simplify (if you can)

• Example:   $\frac{10}{8}\rightarrow\ 1\ \frac{2}{8}\rightarrow\ 1\ \frac{1}{4}$  

  
  

Open Ended

You try!

 $\frac{2}{3}+\frac{4}{6}=?$  

Open Ended

You try!

 $\frac{4}{7}+\frac{1}{3}=?$  

Dividing Fractions

• Step 1: Multiply the first fraction by the reciprocal of the second fraction (flip!)

• Example:  $\frac{3}{5}\div\frac{2}{6}\rightarrow\ \frac{3}{5}\times\frac{6}{2}$  

Dividing Fractions

• Step 2: Multiply the fractions

• Example:  $\frac{3}{5}\times\frac{6}{2}\rightarrow\ \frac{3\times6}{5\times2}=\frac{18}{10}$  

Dividing Fractions

• Step 3: Simplify (if you can)

• Example:  $\frac{18}{10}\rightarrow\ 1\ \frac{8}{10}\rightarrow\ 1\ \frac{4}{5}$  

  
  

Open Ended

You try!

 $\frac{2}{3}\div\frac{3}{4}=?$  

Open Ended

You try!

 $\frac{4}{5}\div\frac{1}{3}=?$  

Poll

How do you feel about multiplying fractions?

• Awesome!

• Pretty good

• Okay

• Not good

Poll

How do you feel about adding fractions?

• Awesome

• Pretty good

• Okay

• Not sure

Poll

How do you feel about dividing fractions?

• Awesome

• Pretty good

• Okay

• Not good