Unit 1 Investigation 2: Multiplication

Comparing Products

100

Just by looking, which of the following would have a greater product than 10 x 25=

a. 10 x 20

b. 2 x 30

c. 15 x 25

d. 5 x 50

c- 15 x 25

200

Just by looking, which of the following would have a greater product than 20 x 30=

a. 40 x 15

b. 20 x 3

c. 200 x 3

d. 3 x 300

d- 3 x 300

300

Just by looking, which of the following would have a greater product than 50 x 25=

a. 5 x 250

b. 50 x 20

c. 25 x 50

d. 50 x 200

d- 50 x 200

400

Just by looking, which of the following would have product EQUAL TO 40 x 10=

a. 40 x 20

b. 30 x 10

c. 20 x 20

d. 400 x 10

c- 20 x 20

500

Just by looking, which of the following would have a product equal to 22 x 15=

a. 11 x 30 

b. 22 x 10

c. 44x 15

d. 11 x 15

a- 11 x 30

2 digit by 2 digit: Area Model

100

12x23=

200+40+30+6=

276

200

43x25=

800+60+200+15=

1,075

300

76x38=

2100+180+560+48=

2,888

400

39x48=

1200+360+240+72=

1,872

500

98x76=

6300+560+540+48=

7448

2 digit by 2 digit:Standard Algorithm

100

25 x 50 =

1,250

200

53 x 21 = 

1,113

300

42x 48 =

 2,016

400

82 x 97 =

7,954

500

98 x 76 =

7,448

Estimation in Multiplication

100

Estimate 31 x 48

31 is close to 30

and 

48 is close to 50

so... 30 x 50 = 1500

200

Estimate 98 x 12

98 is close to 100

and 

12 is close to 10

so... 100 x 10 = 1000

300

Estimate 16 x 218

16 is close to 20

and 

218 is close to 220

so... 20 x 220 = 4400

400

Estimate 103 x 247

103 is close to 100

and 

247 is close to 250

so... 100 x 250 = 25,000

500

Estimate 84 x 46

84 is close to 80

and 

46 is close to 50

so... 80 x 50 = 4000

Story Problems

100

Rory reads for 24 nights in March. Each night, she reads 7 chapters. How many chapters does Rory read in March?

168 chapters. 

200

Lorelei has 31 guests staying at the Dragonfly Inn each night for 29 nights in the month of May. How many guests total stayed at there in May?

899 guests

300

Emily is throwing a huge party! She is inviting 76 guests, and each person's meal will cost $88. How much is Emily spending on everyone's meals altogether?

$6,688

400

Suki is baking desserts for an event! She is baking 12 apple tarts and five times as many eclairs. She also needs to make 15 pavlovas. How many total desserts will Suki bake for the event?

12 tarts x 5 = 60 eclairs

Then, 12 tarts + 60 eclairs + 15 pavlovas = 87 desserts.

500

Michel doesn't have the best attitude. On average, he frustrates 568 people per year. He is 36 years old, and has been frustrating people since he was 12. How many people has he frustrated in his lifetime?

How many years has Michel frustrated people? 36 - 12 = 24 years.

24 years x 568 ppl per year = 13,632 people