Review Fractions

Review :

Fractions

-add and subtract fractions

-change fractions to decimals

Multiple Choice

Think: When adding and subtracting fractions, which rule is true?

• There must be a common denominator 
  

  
   $\frac{5}{8}\ +\ \frac{1}{8}$  

• There must be a common numerator
  
   $\frac{3}{10}\ +\ \frac{3}{5}$  
  

When adding or subtracting fractions, there MUST be a common denominator!

https://youtu.be/Ekbjz0LLKxI

Multiple Choice

Practice: Rewrite this problem so that it has a common denominator.

 $\frac{4}{5}\ -\ \frac{1}{2}$  

•  $\frac{8}{10}\ -\ \frac{2}{4}$  

•  $\frac{4}{5}\ -\ \frac{1}{5}$  

•  $\frac{8}{10}\ -\ \frac{5}{10}$  

Multiple Select

Practice: Rewrite this problem so that it has a common denominator.

 $\frac{2}{9}\ +\ \frac{1}{3}$  

•  $\frac{2}{27}\ +\ \frac{1}{27}$  

•  $\frac{2}{9}\ +\ \frac{3}{9}$  

•  $\frac{6}{27}\ +\ \frac{9}{27}$  

Look for shortcuts!

• In the original problem, the denominators were 9 and 3

• 9 is a multiple of 3

• Make 9 the common denominator

• When in doubt, do it the long way

• Otherwise, look for shortcuts!

Multiple Choice

Solve: Find the answer in simplest form.

 $\frac{1}{2}\ +\ \frac{1}{7}$   

•  $\frac{2}{14}$  
  

•  $\frac{9}{14}$  
  

•  $\frac{2}{9}$  

Multiple Choice

Solve: Find the answer in simplest form.

 $\frac{7}{8}\ -\ \frac{1}{4}$  

•  $\frac{5}{8}$  

•  $\frac{6}{4}$  
  

•  $\frac{9}{8}$  

Multiple Choice

Think: When changing fractions into decimals, what do you need to divide?

• Denominator ÷ Numerator

  
  $\frac{2}{3}\ \rightarrow\ 3\ \div\ 2$
  

• Numerator ÷ Denominator
  
  $\frac{2}{3}\ \rightarrow\ 2\div\ 3$

When changing fractions into decimals, always do Numerator ÷ Denominator.

 $\frac{7}{10}\ \rightarrow\ 7\ \div\ 10$  

Multiple Choice

Practice: Rewrite this fraction as a division problem.

 $\frac{11}{12}$  

•  $11\ \div\ 12$  

•  $12\ \div\ 11$  

Multiple Choice

Solve: Use a calculator to change this fraction into a decimal. 

 $\frac{3}{20}$  

•  $15$  

•  $6.\overline{6}$  

•  $0.15$  

Multiple Choice

Think: Without using a calculator, change this fraction into a decimal.

 $8\ \frac{4}{8}$  

• 8.48

• 8.5

• 10.5

When you have a mixed number, use addition to separate the whole number and the fraction.

 $3\frac{13}{15}\ \rightarrow\ 3\ +\ \left(13\ \div\ 15\right)\ =\ 3\ +\ 0.8\overline{6}\ =\ 3.8\overline{6}$  

Multiple Choice

Practice: Use your calculator to change the fraction into a decimal.

 $10\ \frac{8}{9}$  

•  $10.\overline{8}$  

• 12

• 10.89

Multiple Choice

Solve: Use your calculator or use mental math to change the fraction into a decimal.

 $2\frac{3}{4}$  

• 5.75

• 2.34

• 2.75

Poll

What do you think the best strategy for solving this problem would be?

 $5\frac{6}{10}\ +\ 2.5$  

• Change  $5\frac{6}{10}$  to a decimal

• Change 2.5 to a fraction

Multiple Choice

Practice: Rewrite the problem as a problem of decimals.

 $5\frac{6}{10}\ +\ 2.5$ 

• 5.6 + 2.5

• 0.6 + 2.5

• 5.6 +  $2\frac{1}{2}$  

Multiple Choice

Solve: Find the sum.

 $5\ \frac{6}{10}\ +\ 2.5$  

• 3.1

• 7.11

• 8.1

Multiple Choice

Solve: Find the difference using the steps we've learned.

 $6\ \frac{3}{4}\ -\ 4.25$  

• 11.5

• 2.5

• -2.5