Lecture 3 - Basic Math Flashcards
If it is 5 or above
round up
If it is 5 or below
round down
Example 1: Round 325.497 to the nearest whole number
325
Example 2: Round 325.497 to the nearest tenth
325.5
Example 3: Round 325.497 to the nearest hundredth
325.50
True or False: Avoid rounding numbers within a calculation problem. Round at the final step of a calculation problem.
true
Round 0.0357 to 2 significant figures
0.036
Round 3570 to 2 significant figures
3600
Round 325.497 to two decimal places
325.50
How many drops should a patient apply to their eye for the following prescription?
Timolol 2.5 mg/mL – apply 0.2 mg to right eye twice a day
Note: 20 gtt = 2mL
0.2 mg X mL/2.5 mg X 20gtt/mL = 1.6 gtt = 2 drops
When measuring volume in a graduated cylinder calibrated in units of 1
milliliter, would be correct to measure a volume of 17.5 mL but not 17.54 mL, because
the 5 (tenths) is uncertain and no number should follow.
17.53 mL reading
Are the zeros considered significant? 0.0125 g
NO
Are the zeros considered significant? 1250.0g
yes
How many significant figures?
4.58 g
3
How many significant figures?
4.580g
4 (start left to right)
How many significant figures?
0.0458g
3 (Start right to left)
How many significant figures?
4600g
4
Example: 12.5 g + 10.65 g + 8.30 g = 31.45 g = 31.5 g
The result of products and quotients should:
Have no more significant figures than the component with the least # significant figures
Example: 2.466mg/dose x 15 doses
37 mg
5.5 g + 12.35 g + 4.40 g =
22.3g
2.533 mg/day x 15 days=
38mg
Relative amount of two quantities (one to the other) is called a
Example: a:b
ratio
A proportion is the expression of the equality of two ratios.
Example: a/b = c/d
If 3 tablets contain 975 milligrams of aspirin, how many milligrams should be contained in 12 tablets?
3 tab/975mg = 12 tab/Xmg
X = 3900 mg
If 3 tablets contain 975 milligrams of aspirin, how may tablets should contain 3900
Milligrams?
3 tab/975 mg = Xtab/3900 mg
X = 12 tab
Dimensional analysis steps are?
-Identify the wanted unit of the answer
-Identify given quantities of measurement
-Identify conversion factors
-Set up ratios that can canel
-Compute
How many fluidounces are there in 2.5 liters (L)
Floz = 2.5 L| 1000 mL/ 1L| 1 floz/29.57 mL
Floz = 84.55
liter (l or L)
deciliter (dl)
milliliter (ml) (aka cubic centimeter cc)
1l = 10 dl = 1,000 ml
1dl = 0.1 l = 100 ml
1ml = 0.001 l = 0.01 dl
Volume
kilogram (kg) 1kg = 1,000 g
gram (g) 1g = 0.001 kg = 1,000 mg
milligram (mg) 1mg = 0.001 g = 1,000 mcg
microgram (mcg or μg) 1 mcg = 0.001mg = 0.000001 g
Nanogram (ng) 1ng = 0.000000001 g
Weight
meter (m) 1 m = 100 cm
centimeter (cm) 1 cm = 10 mm
millimeter (mm) 1 mm = 1,000 μm (micrometers)
Length
pound (lb) 1 lb = 16 oz
ounce (oz) 1 oz = 437.5 gr
grain (gr)
AVOIRDUPOIS SYSTEM
gallon (gal) 1 gal = 4 qt
quart (qt) 1 qt = 2 pt
pint (pt) 1 pt = 16 fl oz
Fluid
teaspoon (tsp) 1 tsp = 5 ml
tablespoon (tbsp or T) 1tbsp = 3 tsp = 15 ml
1 cup = 8 fl oz
other
1 m = 39.37 in
1 in = 2.54 cm
Length Conversions
1 fluidram (fʒ) = 3.69 mL (1 fluidram = 1 tsp or 5 ml is accepted value)
1 fluid ounce (f℥) = 29.57 ml (will accept 1 fluid ounce = 30 ml)
1 pt (16 fl oz) = 473 ml
1 qt (32 fl oz) = 946 ml
1 gal = 3785 ml
1 mL = 20 drops (gtt)
Volume Conversions
1 g = 15.432 gr
1 kg = 2.20 lb (avoir.)
1 gr = 0.065 g or 65 mg
1 oz (avoir.) = 28.35 g
1 lb (avoir.) = 454 g
Weight Conversions
