How can I find the unknown number in a

number sentence?

May 2, 2013

Pop Quiz1. What is the unknown number in the following number sentences? n + 12 = 16 45 - _____ = 34 x 9 = 72 108 ÷ 9 =

2. What do we call the symbols that represent the unknown number?

n = 4

11

8 12

Variables

VariablesAre symbols that represent unknowns in a

number sentence. They can be shapes, pictures, letters and fill-in-the-blanks.

The case of the missing number.

Use your resources to

help you solve each case.

Case 1Gift Bags

Sara and James are making gift bags for their party guest. If they have 36 party favors, how many gift bags can they fill if they are putting 3 favors in each bag?

Clues

• 36 party favors

• 3 favors per bag

• How many bags can they fill

36 ÷ 3 =

or

X 3= 36

12

12

Case 2 Dog Days

Clues

Spot spots a squirrel and decides to chase after it. If he chases 5 squirrels per hour how many will he chase in 6 hours?

• 5 squirrels per hour

• How many will he chase

in 6 hours?

5 x 6 =Or

÷ 5 =

6

30

30

Case 3Monkey Business

Margo Monkey has a bunch of 35 bananas to share with her friends. If there are six friends plus herself how many bananas will everyone get?

You’re on

your own

now super

math

sleuths.

Remember

to write

down your

clues and

the problem

you need to

solve.

Can you close this case?

Case 3Monkey Business

Margo Monkey has a bunch of 35 bananas to share with her friends. If there are six friends plus herself how many bananas will everyone get?

Can you close this case?

Clues

• 35 bananas to

share• 6 friends plus

self…hmmm 6+1

=7• How many

will everyone

get?

35 ÷ 7 =

5 =

YOU DID IT!