Chapter 10 Math 283
• Division. Let’s say you want to divide 100 by 20. Enter the dividend
(100), press the (÷) key, and enter the divisor (20). After pressing the
(=) key, the quotient (5) will appear on the display.
• Calculating a percentage. Say you need to identify 20% of 50. Enter
50, press the (×) key, then enter 20, and then press the (%) key. The
answer, 10, will appear on the display. If your calculator does not have
a (%) key, you can calculate this percentage by multiplying 50 by 0.2.
Introduction to Algebra
Algebra is the branch of mathematics that substitutes letters for num-
bers to solve for unknown quantities. The term algebra comes from the
Arabic al-jebr meaning “reunion of broken parts.” Algebra problems are
designed to solve a problem with the answer represented by a letter—typi-
cally x or y. When you learned how to solve for x in the Proportions section
of this chapter, you were using algebra. This section will briefl y explain
how algebra can be used while treating patients.
The mathematics involved in an algebraic equation are like a balancing
scale (recall the scale used to illustrate the scale of justice). What is done on
one side must be done to the other side to balance the scale. In the case of an
algebra problem, what is done to one side of the problem must be done to
the other. Moving from arithmetic (simple math including, addition, subtrac-
tion, multiplication, and division) to algebra will look something like this:
Arithmetic: 3 + 4 = 4 + 3
Algebra: x + y = y + x
The examples above are equations. An equation consists of expres-
sions (collections of numbers and letters) separated by an equal sign. The
two sides of the equation must be equal, like a scale that has equal weights
on both sides.
When solving an algebra problem, you must fi rst write out the equa-
tion and identify the unknown quantity you plan to solve for. Then, use
your basic arithmetic skills—addition, subtraction, multiplication, and
Calculator Uses in Healthcare
1. Karen works in the accounting department of Eastridge Hospital. Her
boss has asked her to calculate how many employees make over
$50,000 each year. Karen fi nds that the hospital employs 450 people.
75 employees make over $50,000. What is the percentage of employees
who make over $50,000?
2. Gail is studying to become a cardiac care nurse. She learns that the heart
pumps about 65 milliliters of blood every time it beats. Gail measures her
own pulse and fi nds that her heart beats 75 times per minute. How many
milliliters of blood does Gail’s heart pump per minute? per hour?
Real Life Scenario
algebra
branch of mathematics
that substitutes letters for
numbers; involves solving
for the unknown
equations
mathematical statements
containing expressions
composed of both numbers
and letters; two sides of an
equation are separated by
an equal sign and must be
equal to one another