© 1999 T
EXAS
I
NSTRUMENTS
I
NCORPORATED
TI-34 Û: A Guide for Teachers
32
Sewing Costumes—Fractions
Overview
Students will use the fraction capability of the
TI-34
Û
calculator to determine if enough material is
available to make a given number of costumes. They
will also determine how much more is needed or how
much extra they have.
Math Concepts
• multiplying
mixed numbers
by whole
numbers
• subtracting
mixed numbers
Materials
• TI-34 Û
• pencil
• student activity
(page 34)
Introduction
Set up the activity by discussing the concepts of
multiplying mixed numbers by whole numbers, and
subtracting mixed numbers.
1. Have students practice multiplying mixed
numbers by whole numbers (and simplifying
where necessary):
a. 3
3
/
5
x 7 25
1
/
5
b. 9
7
/
8
x 4 39
1
/
2
c. 4
1
/
7
x 5 20
5
/
7
d. 7
4
/
5
x 3 23
2
/
5
2. Have students practice subtracting mixed
numbers.
a. 4
5
/
8
- 3
4
/
5
33
/
40
b. 9
7
/
8
- 6
3
/
4
3
1
/
8
c. 5
5
/
6
- 3
1
/
9
2
13
/
18
d. 8
1
/
3
- 7
4
/
7
16
/
21
³ Be sure that the calculator is
in mixed-number mode by
pressing % ~ and
pressing " or ! to select the
mixed number mode.
A
−−bÌÌc
d/e
³ To enter the first problem,
press
3
@
3
>
5
V
7
<.
3−−3ÌÌ5¿¿7
25ËË1ÌÌ5
³ To simplify, press }
<.
Activity
Present the following problem to students:
You are sewing costumes for a dance festival. Each
costume takes 2
3
/
8
yards of material. You have
23 yards to make 14 costumes. Do you have
enough?
If you do, do you have any extra? How much? Do
you need more? How much?
If the material cost $3.98 per yard, how much will
it cost to buy the additional material?
How many costumes could you make with the
material you have?
What if each costume only required 1
2
/
3
yards?
Would you have enough?
³ Before starting the problem,
set your calculator for two
decimal places by pressing
% ‚
2
.
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