Mental Math: Estimate Quotients

Mental Math: Estimate Quotients

pp.260-261

Review Questions

Open Ended

1. Tisha collects old books. She has 2 shelving units, and each shelving unit has 3 shelves. Each shelf holds 12 books . If both shelving units are filled with books, how many books does Tisha have in all?

Open Ended

2. Shannon delivered 135 blueberry muffins to each of 7 restaurants. How many muffins did Shannon deliver?

Multiple Choice

3. Which is NOT a way to find 56 x 9?

• (50 x 9) + 54

• (50 + 9) x (6 + 9)

• (50 + 6) x 9

• (50 x 9) + (6 x 9)

Open Ended

4. Larry reads the same number of pages each night. After 7 nights , he has read a total of 140 pages. How many pages did Larry read of his book each night?

Open Ended

5. The cafeteria ordered 23 boxes of peach yogurt and 57 boxes of raspberry yogurt. Each box contained 6 cups of yogurt. How many cups of yogurt did the cafeteria order?

Open Ended

What compatible numbers can you use to estimate 132   $\div$  6?

Open Ended

Why is rounding not a good way to estimate 132   $\div$  6?

Convince Me!

120 and 6 are compatible numbers. ; 120  $\div$  6 = 20 ; 132 rounded to the nearest ten is 130  or to the nearest hundreds in 100. Neither number is easy to divide mentally.

Open Ended

In the problem on the previous page, if Max uses 80 rubber bands to make each ball, will Max be able to make more or fewer balls than he wanted?

Do You Understand?

#1 fewer balls.; He wanted to make 9 balls, but he would need at least 720 rubber bands, and he only has 700 rubber bands.

Open Ended

Max decides to use 700 rubber bands to make 8 balls. Is it reasonable to say he would use about 90 rubber bands to make each ball? EXPLAIN.

Do You Understand?

#2 Yes; 700 is close 720, and 720  $\div$  8 = 90 rubber bands per ball.

ESTIMATE EACH QUOTIENT.

Use multiplication or compatible numbers.

Show your work.

Open Ended

 $48\ \div5$  

 $48\ \div5$  

about 10 ;  50  $\div$  5 = 10

Open Ended

 $235\ \div8$  

 $235\ \div8$  

about 30 ;   240  $\div$  8 = 30

Open Ended

 $547\ \div6$  

 $547\ \div6$  

about 90 ;   540  $\div$  6 = 90

Open Ended

 $192\ \div5$  

 $192\ \div5$  

about 40 ;   200  $\div$  5 = 40

Open Ended

 $662\ \div8$  

 $662\ \div8$  

about 80 ;   640  $\div$  8 = 80

Open Ended

 $362\ \div3$  

 $362\div3$  

about 120 ;  $360\ \div3$  = 120

Open Ended

 $41\ \div2$  

 $41\div2$  

about 20 ;  $40\ \div2$  = 20

Open Ended

 $211\ \div4$  

 $211\div4$  

about 50 ;  $200\div4$  = 50