Expressions
Evaluate:
6×(10×2)
120
True or False? And why?
25×8=8×25
True. The numbers are just flipped.
Use doubling and halving to rewrite:
24×50
12×100=1,200
A rectangular prism is 4 units long, 3 units wide, and 2 units high. How many unit cubes fill it?
4×3×2=24 cubic units
360÷30= ?
12
Evaluate:
(8×2)×5
80
True or False? And why?
42×16=(42×10)+(42×6)
True. 10+6 = 16
Solve using 10× and 5× :
15×24
(10×24)+(5×24)
240+120=360
A box has 15 objects in each layer and 6 layers. How many objects are in the box?
15×6=90
4 friends earn $74 and split the money equally. How much does each friend get?
74÷4=$18.50
Write a numerical expression:
“To find 18×15, I double 15 and halve 18.”
(15x2)x(18÷20) = 30x9
True or False? And why?
36×11=(36×10)+(2×36)
False. That would represent 36×12.
Solve by multiplying by 10 and removing one group:
34×9
340−34=306
(34x10) - (34x1)
A rectangular prism has a 7 × 5 base and is 4 layers high. What is its volume?
(7×5)×4
35×4=140 cubic units
A box contains 288 balls. Each layer contains 24 balls. How many layers are there?
288÷24=12 layers
Write a numerical expression:
“To find 32×9, I multiply 32 by 10 and then remove one group of 32.”
(32x10) - 32
Fill in the blank WITHOUT finding 150×18 first:
150×18=9×____
18 was halved to 9, so 150 must be doubled to 300.
Solve using doubling and halving:
32×25
16×50=8×100=800
A box has a 12 × 8 base and 5 layers. Find its volume.
(12×8)×5
96×5=480 cubic units
There are 95 students going on a field trip. Each van holds 12 students. How many vans are needed?
95÷12=7 R 11
They need 8 vans because everyone needs a seat.
Write an expression for the volume of a box with a 17 × 12 base and 8 layers. Multiply the dimensions of the base first.
(17x12) x 8
Fill in the blanks:
36×98=(___×36)−(2×36)
100 because 98=100−2.
Solve using a helpful number relationship:
49×36
(50×36)−(1×36)
1,800−36=1,764
A rectangular prism has a volume of 360 cubic units. Each layer contains 45 unit cubes. How many layers does it have?
360÷45=8 layers
A teacher has 250 pencils and puts 24 pencils in each container. How many full containers can she make, and how many pencils are left over?
250÷24=10 R 10
10 full containers and 10 pencils left over.