Comparing Fractions Using Multiples

Comparing Fractions Using Multiples

That have different denominators and different numerators

Multiple Choice

16 is a multiple of 4.

• True

• False

When two fractions have different denominators, you have to change the denominator by finding the common multiple in order to compare them.

Let's compare two fractions on the next slide using common multiples

Compare

 $\frac{3}{6}$  and  $\frac{10}{12}$  

•  Make a list of the multiples of 6 and 12 and find the least common multiple 

• 6: 6, 12, 18, 24

• 12: 12, 24, 36

• Notice they have 12 and 24 in common but 12 is the least common multiple, so we would use 12 

 $\frac{3}{6}$  and  $\frac{10}{12}$  

What do we do next since we found the least common multiple 12 between them?

• We will change the denominator of  $\frac{3}{6}$  by multiplying it by  $\frac{2}{2}$  which equals  $\frac{6}{12}$  

• Now we know that  $\frac{3}{6}$  <  $\frac{10}{12}$  because  $\frac{6}{12}$  <  $\frac{10}{12}$  

Multiple Choice

What is the least common multiple you would use to compare

 $\frac{2}{9}$  and  $\frac{1}{3}$  

• 3

• 9

• 18

• 27

Multiple Choice

 Which choice is the correct multiples for  $\frac{3}{4}$  and  $\frac{7}{8}$  

• 4: 4,16,30
  8:8,16,24

• 4:4, 8, 12, 16, 20
  8: 8, 16, 24, 32

• 4: 4, 8, 12, 15, 19
  8: 8, 16, 23

Multiple Choice

 $\frac{3}{4}\ \ \ \ \ \ \ \ \ \ \ \frac{7}{8}$  

• =

• <

• >

Multiple Choice

What is the least common multiple for the fractions $\frac{2}{3}$  and  $\frac{3}{5}$  

• 9

• 30

• 15

• 12

Multiple Choice

 $\frac{2}{3}$         $\frac{3}{5}$  

• >

• <

• =

Multiple Choice

How do you change the denominator of  $\frac{2}{3}$   to 15 

• Add denominator 3 plus 12 to get 15 then add the numerator 2 plus 12 to get  $\frac{14}{15}$  

• Multiply the denominator  3 x 5 and leave the numerator alone to get  $\frac{2}{15}$  

• Multiply both the numerator and denominator by 5 to get  $\frac{10}{15}$