Compatible Numbers and Rounding
Nicolette had 14 boxes of candy canes. Each box contained 37 candy canes. Use rounding to estimate how many candy canes Nicolette has in all.
14 Rounds to 10
37 Rounds to 40
10 x 40 = 140 Candy Canes
Draw an array for 12 x 8 and solve.
Check answers for array.
12 x 8 = 96
The ice cream shop uses 20 sprinkles on each ice cream cone. That day, the ice cream shop sold 37 ice cream cones.How many sprinkles were used on the ice cream cones?
37 x 20 =
740 Sprinkles
Using break apart, what is one way to solve 45 x 72? Solve.
45 x 72 =
(40 + 5) x (70 + 2) =
(40 x 70) + (40 x 2) + (5 x 70) + (5 x 2) =
2,800 + 80 + 350 + 10 =
3,240
Use partial product to solve 23 x 78
(Hint: Sing "Right right, Right left...)
23 x 78 =
24 + 160 + 210 + 1,400 =
1,794
Use compatible numbers to solve 47 x 29
(Remember: Compatible numbers are the closest things you can round to that make the problem easier)
47 is compatible with 45
29 is compatible with 30
45 x 30 = 1,350
Draw an array for 23 x 97 and solve.
Check answers.
23 x 97 = 2,231
Marcus had made 14 toy cars. Each car uses 30 screws. How many screws does Marcus need to build the toy car?
14 x 30 =
420
Using break apart, what is another way to solve 45 x 72?
45 x 72 =
45 x (70 + 2) =
(45 x 7) + (45 x 2) =
315 + 90 =
405
Use partial product to solve 86 x 48
(Hint: Sing "Right right, Right left...)
86 x 48 =
42 + 640 + 240 + 3,200 =
4,128
There are 22 containers of cookies that Nathaniel made for his class. There were 34 cookies in each container. Use compatible numbers to estimate how many cookies Nathaniel has made in all.
22 is compatible with 20
34 is compatible with 35
20 x 35 = 700 cookies
Draw an area model for 12 x 23 and solve.
Check answers for area model.
12 x 23 =
(10 + 2) x (20 + 3) =
(10 x 20) + (10 x 3) + (2 x 20) + (2 x 3) =
200 + 30 + 40 + 6 =
276
Breanna wants to eat 27 packs of bags. There are 47 bagels in each pack. If Breanna eats all packs of bagels, how many bagels would she have eaten.
27 x 47 =
1,269
Use break apart to solve 23 x 82
23 x 82 =
(20 x 3) + (80 x 2) =
(20 x 80) + (20 x 2) + (3 x 80) + (3 x 2) =
1,600 + 40 + 240 + 6 =
1,886
Use partial product to solve 27 x 84
27 x 84 =
28 + 80 + 560 + 1,600 =
2,268
Marco has made 46 trips to the ice cream store. Each trip took 23 minutes to take. How many minutes did it take Marco in all to finish his trips to the ice cream store? Use rounding to estimate your answer.
46 rounds to 50
23 rounds to 20
50 x 20 = 1,000 Minutes
Adrianna has 46 bags of Hershey kisses. There are 32 kisses in each bag. How many Hershey kisses does Adrianna have in all? Draw an area model to show your work and solve.
Check answers for area model.
32 x 46 =
(30 +2) x (40 + 6)=
(30 x 40) + (30 x 6) + (2 x 40) + (2 x 6) =
1,200 + 180 + 80 + 12 =
1,472 Hershey Kisses
1,472 Hershey Kisses
Gianna ran 14 miles on Saturday and 34 miles on Sunday. If she keeps this pace, how many miles would Gianna be able to run in 12 months?
Step 1:
14 + 34 = 48
Step 2:
48 x 12 = 576
34 x 82 =
(30 + 4) x (80 + 2) =
(30 x 80) + (30 x 2) + (4 x 80) + (4 x 2)
2,400 + 60 + 320 + 8 =
2,788
Use partial product to solve 67 x 42
67 x 42 =
14 + 120 + 280 + 2,400 =
2,814
Liam has 89 shells in each container that he collected from the beach. He had 54 containers in all. Use estimation to find how many shells Liam collected in all.
Solve the actual problem using any strategy you would like to check if your answer is reasonable.
89 rounds to 90
54 rounds to 50
90 x 50 = 4,500
89 x 54 = 4,806
My answer is reasonable.
Penelope ordered a box of stamps that came with 13 large stamps and 43 small stamps. How many stamps come in an order of 16 large stamps? Draw an array and solve.
Check answers for arrays.
13 x 16 = 208 Stamps.
Sofia was baking Christmas cookies. For recipe #1, she used 34 cups of sugar for each 38 cookies. For recipe #2, she used 12 cups of sugar for each 26 cookies. How many more cups of sugar does Sofia use in the first recipe than in the second recipe?
Step 1:
34 x 38 = 1,292
Step 2:
12 x 26 = 312
Step 3:
1,292 - 312 = 980 more cups of sugar
82 x 43 =
82 x (40 + 3) =
(82 x 40) + (82 x 3) =
3,280 + 246 =
3, 526
Use partial product to solve 75 x 93
75 x 93 =
15 + 210 + 450 + 6,300 =
6,975