Estimation
34 x 87
30 x 90 = 2,700
34 x 10 =
30 x 10 = 300
4 x 10 = 40
300 + 40 = 340
What are the partial products?
46 x 35 =
5 x 40 = 200
30 x 5 = 150
30 x 40 = 1,200
What is the expanded form?
57 x 65
(50 + 7) x (60 + 5)
Joey reads 15 pages of his book each night for two weeks. How many pages does he read altogether?
15 x 14 = 210 pages
Estimate:
72 x 52
70 x 50 = 3,500
75 x 40
70 x 40 = 2,800
5 x 40 = 200
2,800 + 200 = 3,00
Solve:
43 x 89 =
3,827
What is the missing piece of this property?
59 x 76 = 76 x ____
What property is this?
59
Commutative Property
A cleaning service charges $13 for floors and $25 for bathrooms. If the service cleans 27 total floors and bathrooms, how much money did they make?
13 + 25 = 38
38 x 27 = $1,026
Estimate:
82 x 93
80 x 90 = 7,200
85 x 30 =
80 x 30 = 2,400
5 x 30 = 150
2,400 + 150 = 2,550
56 x 89 =
9 x 6 = 56
9 x 50 = 450
80 x 6 = 4,800
80 x 50 = 400
NO!!
9 x 6 = 54
9 x 50 = 450
80 x 6 = 480
80 x 50 = 4,000
I am a number. When you multiply any number by me the answer is ME!!
What number am I?
ZERO!!
Larry runs 18 laps 16 times in June
and 19 laps 15 times in July. How many total laps
did Larry run?
June: 18 x 16 = 288 laps
July: 19 x 15 = 285 laps
288 + 285 = 573 total laps
Estimate:
13 x 76
10 x 80 = 800
23 x 90 =
20 x 90 = 1,800
3 x 90 = 270
1,800 + 270 = 2,070
Is this product REASONABLE?
57 x 50 = 2,850
50 x 50 = 2,500
No,
57 rounds to 60
60 x 50 = 3,000
I am a number. When you multiply any number times me, you keep the number.
What number am I?
ONE!!
Melissa needs 38 beads for every necklace she is making. If she needs to make 58 necklaces for the holidays, what is the BEST ESTIMATE for how many beads she may need?
38 x 58 =
40 x 60 = 2,400 total beads
Estimate:
58 x 86
60 x 90 = 5,400
77 x 70 =
70 x 70 = 4,900
7 x 70 = 490
4,900 + 490 = 5,390
What is the missing factor?
____ x 30 = 2,400
80 x 30 = 2,400
What is expanded form of:
76 x 54
(70 +6) x (50 + 4)
Johnny tells 23 pizzas on Friday and 17 pizzas on Saturday. If he makes $22 per pizza, how much money will he make that weekend?
23 + 17 = 40 total pizzas
40 x 22 = (40 x 20) + (40 x 2)
= 800 + 80
= $880