Relating Relating Multiplication with Multiplication with

DivisionDivision

Relating Relating Multiplication with Multiplication with

DivisionDivision

Let’s Remember:• We know our fact families:

– 5 x 7 = 35 35 = 5 x 7– 7 x 5 = 35 35 = 7 x 5– 35 ÷ 7 = 5 5 = 35 ÷ 7– 35 ÷ 5 = 7 7 = 35 ÷ 5

We also can reverse a multiplication or division number sentence. For example:

We can reverse a multiplication sentence to make a division number sentence. For example:

9 x 11 = 99

99 ÷ 11 = 9

Let’s See that Again45 ÷ 9 = ____

Now, was that so hard?

You TryWrite a Related Multiplication or

Division Sentence:9 x 12 = 108 95 x 4 = 380

450 ÷ 10 = ____ 132 ÷ 11 = ___

Jacob solved the following multiplication equation:

23 x 8 = 184

What number sentence could he use to check his answer?

D 100

23 x 8 = 184

184 ÷ 8 = 23

or 184 ÷ 23 = 8

D 100

Problem Solving – A division problem that

you can solve with multiplication

Last year there were a total of 78 students in the 4th grade classes of Encarnacion, Boynton and Hamme. If each class has the same number of students, how many students were in each class?

Think – “Zzzz”There are a total of 78 students in the 4th

grade classes of Encarnacion, Boynton and Hamme. If each class has the same number of students, how many students are in each class?

Division – I know the total78 ÷ 3 = ?

? x 3 = 78

Tutters says, “Meowwww… it’s your turn!”

D 200

Gabrielle solved the following math problem:32 x 4 = 128

What number sentence could she use to check her answer?

128 128 ÷ 4 = 32÷ 4 = 32

32 x 4 = 128

D 200

• Now – don’t let the variables in the next problems scare you!

D 400

If 48 ÷ n = 6

What does 6 x n = ?

48

because n = 8

48 ÷ 8 = 6

6 x 8 = 48

D 400

True or False

The following statement is correct:

If n x 3 = 18, then n = 18 ÷ 3

D 300

True

because…

If n x 3 = 18, then n = 18 ÷ 3

n = 6

6 x 3 = 18

6 = 18 ÷ 3

D 300

ZZZZ

N x 3 = 18

True or False

The following statement is correct:

If 5 x f = 35, then 35 = 5 ÷ f

D 300

False

because…

If 5 x f = 35, then f = 7

And 35 = 5 ÷ 7?

NO WAY!

D 300

ZZZZZZ

5 x f = 35

Focused and alert, no sleeping now!

So… if all I have to do is reverse the number sentence?

• What is another way to write the equation 308 ÷ n = 14 ?

a. 14 + n = 308b. 14 x 308 = nc. 14 x n = 308d. 308 – 14 = n

(Let’s just reverse the number sentence in the question. 14 x n = 308, so c is our answer!)

Well, how about with variable

NWhat is another way to write the equation

N x 24 = 120?

a. N = 24 ÷ 120

b. N = 120 ÷ 24

c. N = 24 x 120d. N x 120 = 24 (Let’s just reverse the number

sentence in the question. 120 ÷ 24 = N, so b is our

answer!)

What is another way to write the

equation 54 ÷ n = 6?

a. n = 9 x 6b. n = 54 x 6c. n = 54 ÷ 6d. n = 54 x 9

(THINK – What number could n be? Which answer choice makes sense for that number?)

• Write a related equation for the following number sentences:

36 ÷ 6 = 6 25 ÷ 5 = 572 = 9x 8 6 x 7 = 42

y ÷ 4 = 5 3 x b = 6c = 8 x 2 d ÷ 10 = 9

– Find the value of the variable (letters) in the last four equations.

Which statement is correct?

A. If a ÷ 3 = 7, then a = 7 x 4

B. If 5 x 6 = b, then 6 x b = 5

C. If 14 ÷ y = 2, then y = 14 x 2

D. If d = 24 ÷ 6, then d x 6 = 24

D 500