# Multiplication Review ```Name _______________________________________ Periods _________ Date _______
Multiplication Review
Unit Vocabulary:
Factor – the numbers you are multiplying
Product – the answer to a multiplication problem
Variable – a letter used to represent a number in an equation
Algorithm – a set of procedures for solving a problem
Array – a representation of a multiplication problem – is square or rectangular – one factor
is represented across the top of the array while the second factor is represented along the
side of the array – the product is the area of the array
Properties of Multiplication
 Identity property – in multiplication – any number multiplied by one will have the
original number as the product example: 9 x 1 = 9
 Commutative property – the order in which you multiply numbers does not affect
the product example: 5 x 3 = 3 x 5
 Associative property – the way that the factors are grouped does not change the
product example: 3 x (4 x 5) = (3 x 4) x 5
 Zero property – any number multiplied by zero will result in a product of zero
example: 8 x 0 = 0
 Distributive property – multiplying the sum of two numbers by another number,
is equivalent to multiplying each of the addends by that number and then adding
the products together. Here is a friendlier description and example:
45 x 6 – First we must distribute the 45 into friendly numbers – numbers
that we can multiply mentally. 45 can be split into 40 plus 5. Next, multiply each
of the numbers by 6. 40 x 6 = 240 and 5 x 6 = 30. Add the sums of the products
240 + 30 = 270. So….45 x 6 = 270.
The distributive property would be written this way:
45 x 6 = (40 x 6) + (5 x 6) OR 45 x 6 = (40 + 5) x 6
Solve each equation and decide which multiplication property helps you solve the equation.
1.) 4 x 5 x 2 = n _________________________________________________________________
2.) 8 x (3 x 2) = n ________________________________________________________________
3.) 16 x n = 16 __________________________________________________________________
4.) 72 x 4 = (70 x 4) + (n x 4) _____________________________________________________
5.) 5 x 8 x 2 = n _________________________________________________________________
6.) 65 x n = 0 ___________________________________________________________________
A Multiplication Short Cut
 When you are multiplying multiples of 10, 100 or 1,000, just write the answer to the
basic fact that is in the problem and then count the zeros in the factors and put that
many zeros in your answer. Example: 400 x 20 = 8,000 (4 x 2 = 8 and there are three
zeros in the factors)
7.) 40 x 50 = ________
8.)
300 x 20 = _________
9.) 8 x 900 = ________
Estimation steps:
 Find the greatest place value. This is the place value that is worth the most. Example:
3,475 – the 3 is in the thousands place, which is worth more than the other place value in
this number.
 Round to that place value.
 Multiply the rounded numbers. First, solve the basic fact. Write that number down.
Count the zeros in both factors. Write that many zeros beside the answer to the fact. Put
commas where they belong.
Example: 3,475 x 75 = about 3,000 x 80 which equals 240, 000
Estimate by rounding to the greatest place.
10.) 45 x 54 _____________________________________________
11.)
872 x 9 _____________________________________________
12.)
8 x 325 _____________________________________________
13.)
5 x 76 ______________________________________________
14.)
123 x 456 ___________________________________________
Arrays
This array shows 28 x 4. The 28 is shown by 2 tens blocks and 8 ones blocks.
There are 4 groups of 28 in the array.
20
4
20 x 4 = 80 and 8 x 4 = 32 so 28 x 4 = 114
8
This array shows 3 x 5, which is 15.
3
5
**Be sure you can outline an array on graph paper!**
Multiplication Methods:
Multiplying by single digit numbers:
2
74 First, multiply the ones places : 5 x 4 = 20. Write the 0 in the ones place
x 5
of the answer and regroup the 2 because it means 20. Next, multiply
370
5 x 7and add on the 2 which was regrouped. 35 + 2 = 37
need more room.
15.) 62 x 7= _________
16.)
93 x 4 = _________
17.) 508 x 9 = _________
Multiplying by two-digit numbers:
Partial Product Algorithms:
78
X
70
8
x 25
20
1,400
160
X 25
350
40
390
5x8=
40
5 x 70 =
350
20 x 8 =
160
20 x 70 = 1,400
1,950
5
1,400 + 160 + 350 + 40 =
1,950
78
Don’t forget to
regroup. When
multiplying by the
+1560
tens place, use a
1,950
zero as a place
holder.
Solve each problem using an algorithm of your choice. Show your work on the back of this
page if you need more room.
18.) 92 x 67 = _________
19.)
80 x 24 = _________
20.)
913 x 57 = _________
Problem Solving
 Addition – taking groups and putting them together to get a TOTAL
 Multiplication – taking EQUAL groups and putting them together to get a TOTAL
 Subtraction – taking the TOTAL and getting rid of part of it or comparing (how much
bigger, smaller, fatter, wider, taller, more, less, etc.)
 Division – taking the TOTAL and splitting it into EQUAL groups
Remember - in addition and multiplication you are calculating a total while in subtraction
and division, you know the total and you are getting rid of or splitting it into groups.
Some problem solving strategies:
 Draw a picture
 Act the problem out in your mind
 Look for patterns
 Guess and check
 Look for clue words for estimation: about, approximately, estimate
Solve each word problem. Show your work.
21.) A purple marlin eats 125 mosquitoes in a day. About how many mosquitoes will a
purple marlin eat in one week?
22.) After a class field trip to an animal habitat, class members can order photographs
to remember the day. Fifteen students out of a class of 26 order two prints each.
The rest of the class ordered three prints each. How many pictures were ordered by
the class?
23.) Sheila’s horse Champion exercises 2 hours each day. Champion eats 105 pounds of
hay each week. How much hay will Champion eat in a year?
24.) It takes Adam’s grandfather 27 hours to carve one wooden bird. How many hours
would it take him to carve 62 birds? (One bird for each 5th grader!!)
25.) If Adam’s grandfather finished 49 carved birds, how many more birds does he have
left to carve so that each 5th grader can have one?
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