Adding and Subtracting Fractions Review

Adding and Subtracting Fractions Review

1/6 2021 Wednesday

Remember when we add or subtract fractions...

• They must have like denominators.

• WE DO NOT ADD THE DENOMINATORS!

How do we find a common denominator?

• Find the multiples (skip counting numbers) of the numerator and the denominator.

• Circle the smallest number the numerator and denominator has in common.

• This is our LCD (Least Common Denominator)!

Lets practice finding the common denominators of these fractions.

1/2 and 3/4

6/10 and 1/3

Multiple Choice

What is the least common denominator of 1/2 and 3/5.

• 2

• 6

• 5

• 10

Let's practice adding these fractions and regrouping!

 $3\frac{1}{2}+\ 2\frac{3}{4}$  

Multiple Choice

Let's put it all together...

combine 1/2 and 3/5

• $1\ \frac{1}{10}$
  

• $\frac{11}{20}$

• $\frac{4}{7}$
  

• $\frac{9}{10}$

OH NO! What if we have to subtract?!

• Step 1: Don't panic.

• Step 2: Find our common denominators.

• Step 3: Convert any mixed numbers to improper fractions or borrow if needed.

• Step 4: Subtract our numerators

Let's practice!

•  $1\ \frac{1}{2}-\ \frac{3}{4}$  

•  $4\ \frac{2}{3}\ -\ \frac{1}{2}$  

Multiple Choice

Show what you know...

 $4\ \frac{1}{6}\ -\ \frac{1}{2}$  

• 3 $\frac{2}{3}$  

• 4 $\frac{0}{4}$  
  

• 22/4

Now we apply what we learned...

• Which operation will we use depends on what the problem is asking us to find?

• Are we finding a total?

• Are we breaking a total apart?

• Sometimes we have to do more than one operation!

Multiple Choice

What operation do we need to solve the problem?

John loves to find imposters in Among Us. He plays 2 & 1/2 hours on Friday and 1 & 3/4 hours on Saturday. How much does he play on these two days combined?

• Add

• Subtract

• Multiply

• Divide

Multiple Select

What operation will we need to solve the problem?

Gwen has 1/2 pound of snickers, 1/3 pound of oreos, and 1/4 pound of kit-kats. She gave her best friend 1/4 of all her candy combined. 

How much candy does Gwen have left?

• Add

• Subtract

• Multiply

• Divide

Multiple Choice

Abed wants to watch the whole series of Who's the Boss on Netflix. Abed already watched 1/2 of the series and this week he binge-watched 3/8 the episodes. How much of the series does he have left?

• 2/8

• 1/8

• 3/4

• 1 Whole

Open Ended

Troy wants to be the best football player so he practices all weekend. Friday he ran for 1 full hour, Saturday he practices his passing for 1 & 3/4 hours, and Sunday he ran drills for 2 & 1/2 hours. How much time did Troy practice altogether?

Open Ended

How can you tell the difference between an addition and a subtraction problem?