Mental Math
Estimating and Multiplying by Tens
Using the Box Method
Standard Method
Word Problems
100
20 x 40 =
What is 800?
100
32 x 83 =
What is 30 x 80 = 2400?
100
Use the box method 18 x 26
What is 10 + 8 and 20 +6 200, 60, 160, 48 468
100
27 x 16 =
What is 432?
100
Why is the product of 15 x 32 the same as the sum of 10 x 32 and 5 x 32?
15 x 32 is the same thing as (10 + 5) x 32 when you break it up.
200
60 x 90 =
What is 5400?
200
79 x 79 =
What is 80 x 80 = 6400?
200
Use the box method 21 x 34
What is 20 + 1, 30 + 4 600, 80, 30, 4 714
200
29 x 15 =
What is 435?
200
Arrowhead Stadium can hold about 80,000 people. Section G has 20 rows, with 15 seats in each row. How many seats total are there in Section G?
What is 300 total seats?
300
50 x 70 =
What is 3500?
300
602 x 43 =
What is 24,000?
300
Use the box method 68 x 17
What is 60 + 8, 10 + 7 600, 80, 420, 56 1,156
300
41 x 12 =
What is 492?
300
The flagpole outside of a school is 12 feet tall. How many inches tall is it? Hint: How many inches are there in ONE foot?
The flagpole is 144 inches tall.
400
900 x 70 =
What is 6300?
400
61 x 202 =
What is 60 x 200 = 12000?
400
Use the box method 21 x 31
What is 20 + 1, 30 + 1 600, 20, 30, 1 651
400
58 x 19 =
What is 1,102?
400
BEU bought 54 sketch pads for 20 classrooms. How many sketchpads did they purchase in all?
The school purchased 1,080 sketch pads.
500
100 x 60 =
What is 6000?
500
8 x 55 =
What is 8 x 60 = 480?
500
Use the box method 43 x 19
What is 40 + 3, 10 + 9 400, 360, 30, 27 817
500
76 x 54 =
What is 4, 104?
500
A rectangular office building is 320 feet long and 80 feet wide. What is the total area of the office building? Hint- Area of a a rectangle is length x width.
What is 2560 square feet?
M
e
n
u