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Learning Log
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• Why would math be important in the health
care area?
• Give 2 examples when we would use it.
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Math is important in
healthcare
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• All health care workers are required to
perform simple math calculations when
doing various tasks.
• Knowing basic math calculations are
essential for all health care professionals to
be successful.
• Mathematical errors in the healthcare arena
may result in injury or a life or death
situation.
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Number forms
• Whole numbers: The counting numbers and
zero; they do not contain decimals or
fractions.
• Non-whole numbers: Numbers that have
decimals
ex: 12.25
• Mixed numbers: Whole numbers and a
fraction
ex: 12 ½
• Percentages: Represents part or all of
something
ex: 12%
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Basic Math
• Addition - the totaling of two or more
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numbers
• Subtraction - the opposite of addition;
taking a number away from another
• Multiplication - a quick easy way to add;
finding the product of two numbers
• Division - the opposite of multiplication;
the process of separating into parts
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Averages
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• The average of a group of numbers is
computed by summing all numbers and
dividing by the number of observations.
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– For example, to compute the average of a
sample of numbers, such as 19, 20, 21, 23, 18,
25, and 26, first sum the numbers:
(19+20+21+23+18+25+26) = 152
– Then calculate the average by dividing this
total (152) by the number of observations (7),
which gives an average of 21.7 or about 22.
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Metric System and
Health Care Applications
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• Why do we use the metric
system in health care?
– To align with the rest of the world
– To assure accurate and consistent
communication in a healthcare
setting
– Because it is based on 10s, you can
do some calculations in your head!
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Image from
www.pocketnurse.com
There are four basic rules to the
Metric System
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1. Numbers indicating less than one unit are always
written in a decimal form, not as a fraction.
– Ex: 1/10 = 0.1
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2. When writing decimals, if there is no number before
the decimal, always write a 0.
– Ex: .1 is 0.1
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3. Abbreviations for metric terms are never plural;
they are always written in singular form.
– Ex: grams is g, not gs
4. Leave a space between the number and the
abbreviation.
– Ex: 8 g or 0.1 dm
It’s Really Very Simple
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1 kilometer =
1 hectometer =
1 dekameter =
1 meter
1 decimeter =
1 centimeter =
1 millimeter =
1,000 meters
100 meters
10 meters
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0.1 meter
0.01 meter
0.001 meter
It’s Really Very Simple
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1 kilometer =
1 hectometer =
1 dekameter =
1 meter
1 decimeter =
1 centimeter =
1 millimeter =
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1 X 103
1 X 102
1 X 101
1 X 100
1 X 10−1
1 X 10−2
1 X 10−3
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We’re Going to Start with These
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1 kilometer =
1 meter
1 centimeter =
1 millimeter =
1,000 meters
0.01 meter
0.001 meter
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Make a Mental Picture
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• Kilometer
• Meter
• Centimeter
• Millimeter
Track around football
2.5 times
field = 400 meters
How far for a kilometer?
Using a meter stick or
ruler, use your body to
make a mental picture of
1 meter, 1 centimeter, and
1 millimeter.
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Meter: about floor to waist
Centimeter: width of index finger
Millimeter: thickness of fingernail
Can you do the math?
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• How many millimeters in a centimeter?
• How many centimeters in a meter?
• How many millimeters in a meter?
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• How many meters in a kilometer?
• How tall are you in meters (estimate)?
What about weight?
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• 1 kilogram =
• 1 gram
• 1 milligram =
1,000 grams
0.001 gram
• Also referred to as mass.
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Make a Mental Picture
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• Kilogram
About the weight of a
half-full 2-liter bottle.
• Gram
The plastic top
weighs 2 grams
A can of soup
contains 300 grams
• Milligram
Approximately 3
grains of salt.
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Can you do the math?
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• How many milligrams in a gram?
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• How many grams in a kilogram?
kilograms?
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• How much did you weigh at birth in
Example: 7.5 lbs = 3.4 kg
Formula: lbs / 2.2 = kilograms
kg x 2.2 = pounds
What about liquid measures?
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• 1 liter
• 1 milliliter = 0.001 liter
• 1 cubic centimeter (cc) = 1 milliliter (mL)
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Make a Mental Picture
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You already know the
volume of a 2-Liter bottle
• Liter
• Milliliter
A can of soda is 240 mL
One teaspoon is 5 mL
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Can you do the math?
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• How many milliliters in a liter?
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• How many milliliters in a coffee mug?
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Converting Grams
• Grams to milligrams – multiply by 1000 or
move decimal three places to the right
• 0.15 g = _____ mg
• 0.150 g = 150 mg
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• 0.15 g = 150 mg
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• Milligrams to grams– divide by 1000 or move
decimal three places to the left
• 500 mg = _________ g
Practice converting grams and kg
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• What would you do to convert grams to
kilograms?
• 600 g = _________ kg
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• What would you do to convert kilograms to
grams?
• 4.5 kg = _________ g
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Converting Meters
• Meters to millimeters – multiply by 1000 or
move decimal three places to the right
• 2.54 m = _____ mm
• 2.540 m = 2540 mm
• Milliliters to liters – divide by 1000 or move
decimal three places to the left
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• 1650 ml = _________ l
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Metric Quiz
1. 0.25 g = ______ mg
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2. 1.5 m = _______ mm
3. 3 mm = ________ m
4. 10 cc = ________ mL
5. 2 mg = _________ g
6. 200 mL = _________ L
7. 88 g = ________ kg
8. 7.5 cm = _______ m
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9. 300 m = ________ km
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10. 10 kg = __________ g
11. 40 mg = _________kg
12. 6 L = _________ mL
Congratulations!
Time to Convert Household Weight
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1 ounce (oz) = 0.028 kg or 28 g
1 pound (lb) = 0.454 kg or 454 g
1 kg = 2.2 lbs (memorize)
To convert lb to kg, divide the number of pounds
by 2.2
145 lb  2.2 = 65.9 kg
To convert kg to lb, multiply the number of
kilograms by 2.2
25 kg x 2.2 = 55 lbs
Stoichiometry
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Now You Try It - Weight
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1. 6 oz = ________ kg
2. 220 lbs = _______ kg
3. 1362 g = ________ lbs
4. 4 kg = _______ lbs
5. 16 oz = _______ g
6. 280 g = ________ oz
7. O.336 kg = ________ oz
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Congratulations!
Time to Convert Household Length
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1 inch (in) = 0.025 meter (m) or 2.54 cm
How many mm in 1 in!
1 foot (ft) = 0.31 meter (m) or 30.48 cm
How many inches in a foot?
How many feet in a yard?
How many meters in a yard?
So…which is longer, a meter stick or a yard
stick?
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Now You Try It - Length
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1. 6 in = ________ m
2. 27.94 cm = _______ in
3. 25 m = ________ in
4. 400 ft = _______ m
5. 15.24 cm = ______ ft
6. 6 ft 2 in = ________ cm
7. 50 m = ________ yards
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Congratulations!
Time to Convert Household Volume
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1 milliliter (mL) = 1 cubic centimeter (cc)
1 teaspoon (tsp) = 5 milliliters (mL)
1 tablespoon (tbsp) = 15 milliliters (mL)
1 ounce (oz) = 30 milliliters (mL)
1 cup = 8 oz = 240 mL
1 pint (pt) = 16 oz = 500 mL
1 quart (qt) = 32 oz = 1000 mL = 1 Liter (L)
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Isn’t That Funny Math?
• If 1 cup = 240 mL, and 2 cups equal one
pint…
• Shouldn’t 1 pint = 480 mL instead of 500 mL?
• Why the funny math?
• The conversions aren’t perfect, but the medical
community accepts the conversions we gave
you on the previous slide.
of math!
2 people
• Now THIS3isout
funny
have trouble with fractions.
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Now You Try It - Volume
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1. 4 mL = ________ cc
2. 20 tsp = _______ mL
3. 20 mL = _______ tsp
4. 4 oz = _______ mL
5. 750 mL = _____ cups
6. 64 oz = ________ pts
7. 9 qts = ________ L
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Congratulations!
Time to Convert Temperature
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• Fahrenheit (F) to Celsius (C) = 0F- 32 x 0.5556
• Celsius (C) to Fahrenheit (F) = 0C x 1.8 + 32
• If you memorize those two formulas,
temperature conversion is fairly easy.
• Get out your calculators!
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Now You Try It - Temperature
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1. 260 F = _______ 0C
2. 32 0F = _______ 0C
3. 102.6 0F = _______ 0C
4. 8
0C
= _______
0F
5. 32 0C = ______ 0F
6. 0 0C = _______ 0F
Round to the
nearest tenth
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Percents
• A percent indicates a value equal to the
number of hundredths.
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– Changing a Percent to a fraction:
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Drop the percent sign (%)
Write the number as the numerator
Write 100 as the denominator
Reduce to lowest terms
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Percents (cont.)
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• Changing a Percent to a decimal:
– Drop the percent sign (%)
– Divide by 100 (by moving the decimal point
two places to the left)
– Express the quotient as a decimal.
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Percents (cont.)
• Finding Percentages of Numbers:
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– Write the number after the word of as the
denominator.
– Write the other number as the numerator.
– Divide the numerator by the denominator.
– Multiply by 100
– Add the percent sign (%)
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Example:
Write as a fraction:
Divide numerator by denominator:
Multiply by 100, add percent sign:
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What is 35 of 90?
35/90
35 ÷ 90 = .39
.39 x 100 = 39%
Now You Try It - Percents
• Change a percent to a fraction:
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25% = ___________
1/4
3/4
75% = ___________
90% = ___________
9/10
Change a percent to a decimal:
.66
66% = ___________
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1.04
104% = ___________
Find percent of a number:
55 of 60 = ________
92%
88%
75 of 85 = ________
5%
6 of 120 = ________
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Roman Numerals
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• Roman Numerals origination
– Many people believe Roman Numerals began
as a tally system used by shepherds to keep
track of how many sheep they had.
– Each sheep was counted with a single notch cut
into a stick with a knife. Every fifth sheep was
recorded with two notches to form a V and then
each tenth sheep was denoted by an X.
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Roman Numerals
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• Reading Roman Numerals
– M=1000, D=500, C=100, L=50, X=10, V=5, and
I=1
– The letters are arranged from left to right in
descending order of valuation and are simply added
to each other.
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Roman Numerals (cont.)
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– Sometimes there’s a lower value numeral in
front of (to the left of) a higher value numeral
to indicate that the lower value should be
subtracted from the adjacent higher value.
– The subtraction rule is particularly useful to
avoid four or more identical, consecutive
numerals. For example, instead of writing IIII,
we write IV.
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Now You Try It –
Roman Numerals
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• Rewrite the following:
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4 = ________
IV
VII
7 = ________
16= ________
XVI
XVIII = ________
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19
XIX = ________
XI = ________
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Ratios
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• A ratio indicates a relationship between two
numbers.
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Ratios (cont.)
4/16
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• Changing a fraction to a ratio
1:4
– Reduce to lowest terms
– Write the numerator of the fraction as the first
number of the ratio
– Place a colon after the first number
– Write the denominator of the fraction as the
second number of the ratio
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Ratios (cont.)
• Changing a percent to a ratio
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– Express the percent as a proper fraction reduced
to lowest terms
– Write the numerator of the fraction as the first
number of the ratio.
– Place a colon after the first number.
– Write the denominator of the fraction as the
second number of the ratio.
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Example:
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Percent as fraction: 25% = 25/100
Reduced :
¼
As a ratio: 1:4
Now You Try It –
Ratios
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• Change the following fractions to a ratio:
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2.
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5/25 = ___________
1:5
1:3
8/24 = ___________
Change the following percents to a ratio:
30/100 = 3/10 = 3:10
30% = ___________
68% = ___________
68/100 = 17/25 = 17:25
15/100 = 3/20 = 3:20
15% = ___________
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