Mental Math

Mental Math- p.256 Word Problems

Open Ended

If you know 20  $$\div$$  5 = 4, how does that help you calculate 200  $$\div$$  5 ?

p.256 #25

Answering 200  $\div$  5  will be much easier upon using the basic fact 20  $\div$  5   =4. I will just need to add zero/s after 4 to match the dividend.

Open Ended

A bakery produced two batches of bread with 80 loaves each hour. It sold 30 loaves each hour.

How many loaves of bread were sold in 4 hours?

p.256 #26

A. 30 loaves ; 4 hours

30 x 4 = 120 loaves

Open Ended

A bakery produced two batches of bread with 80 loaves each hour. It sold 30 loaves each hour. How many loaves of bread were sold in 4 hours?

HOW MANY LOAVES OF BREAD WERE LEFT TO SELL?

p. 256 #25

B. two batches ; 80 loaves in each batch

120 loaves in 4 hours

Question: How many loaves of bread were left to sell?

80 x 2 = 160 loaves

160 -120 = 40 loaves

Open Ended

At the North American Solar Challenge, teams use up to 1,000 solar cells to design and build solar cars for a race. If there are 810 solar cells arranged in 9 rows, how many solar cells are in each row?

p.256 #27

810 solar cells - total ; 9 rows ; ? = solar cells in each row
810   $\div$  9 = 90 solar cells in each row

Open Ended

On Saturday afternoon, 350 people attended a play. The seating was arranged in 7 equal rows. How many people sat in each row?

Draw a bar diagram.

Write and solve an equation.

p. 256 # 28

350 people attended ; 7 equal rows ; p -people in each row
350   $\div$  7 = p ; p = 50 people on each row

p.256 #28

350 people attended ; 7 equal rows ; p -people in each row

350   ÷  7 = p ; p = 50 people

Open Ended

Molly and five friends picked a total of 300 oranges. If each girl picked the same number of oranges, how many oranges did Molly pick.

Explain.

p. 256 #29

Molly and 5 friends = 6 ; a total of 300 oranges
300   $\div$  6 = 50 oranges

There is a total of 6 girls, so 300  $\div$  6. Molly and each of her friends picked 50 oranges.

Multiple Choice

Three dock workers load 240 crates equally onto 8 ships. How many crates are loaded onto each ship?

• 3 crates

• 10 crates

• 30 crates

• 80 crates

p.256 #30

240 crates ; 8 ships

240  $\div$  8 = 30 crates

Multiple Choice

Selena used a basic fact to help solve 180   $$\div$$  6. 

What basic fact did Selena likely use?

 What is 180   $$\div$$  6?

• 180   $$\div$$  3  ; 60

• 18  $$\div$$  3 ;  30

• 18  $$\div$$  6 ; 60

• 18  $$\div$$  6  ; 30

p.256 #31

180   $\div$  6 = ?

18 $\div$  6 =  3 ; 180   $\div$  6 = 30