Texas Instruments TI-15 Teachers Manual page 20

Comparing Costs
What happens if you multiply each solution by
6 to check it?
For the remainder form, you have to multiply
586 x 6 and then add 4 to get the total cost of
$3520. You can multiply 586
form to get $3520. If you enter
press ®, you get
sense because 6 x 7 doesn't end in a 0!
If you enter
586.66667
quotient to hundredths since it is money, and
then find 586.67 x 6, you still get 3520.00, which
still doesn't make sense because 6 x 7 = 42. If you
clear the calculator and enter
press ® , then the display reads
does make sense.
As a school, which form of the quotient would
you want to use?
Responses may vary. Some students may want to
use the decimal form, since it is the closest to the
representation of money. Some students may
want to use the integer quotient and remainder
form and suggest that the Central Office pay the
$4.00 remainder.
Although the fraction form of the quotient
describes the exact quantity that each school
should pay, most students will recognize, by
comparing it to the decimal form, that the
fraction form is not easily translated into money.
© 2000 T I
EXAS NSTRUMENTS
(Continued)
2
/ x 6 in fraction
3
586.666667 x 6
3520 , but that doesn't make
, then fix the decimal
586.67 x 6
3520.02
I
NCORPORATED

and
, and
, which
TI-15: A Guide for Teachers
When you fix
586.666667 to 2
decimal places, and
then multiply by 6, the
calculator "remembers"
the original number and
uses it as the factor.
The product rounded to
the nearest hundredth,
using the original factor,
is 3520.00. When you
enter 586.67, the
calculator uses this
number for the factor,
showing the actual
product of 3520.02.
13