Medical Math Module 2

Flashcards

Metric system: Why is it called a decimal system?

Metric prefixes change unit sizes by powers of 10, making conversions systematic.

Metric system: What does the gram (g) measure?

Mass; the slides refer to it as weight.

Metric system: What does the metre or meter (m) measure?

Length or distance.

Metric system: What does the litre or liter (L) measure?

Volume.

Metric system: Which metric quantities are especially common in medication calculations?

Mass (for example, mg) and volume (for example, mL); length units can also be used clinically.

Metric abbreviations: What does kg mean?

Kilogram.

Metric abbreviations: What does g mean?

Gram.

Metric abbreviations: What does mg mean?

Milligram.

Metric abbreviations: What does mcg mean?

Microgram; µg is another symbol, but mcg can reduce confusion in medication contexts.

Metric abbreviations: What does L mean?

Litre (liter).

Metric abbreviations: What does mL mean?

Millilitre (milliliter).

Metric conversion: How many grams are in 1 kilogram?

1,000 g.

Metric conversion: How many milligrams are in 1 gram?

1,000 mg.

Metric conversion: How many micrograms are in 1 milligram?

1,000 mcg.

Metric conversion: How many millilitres are in 1 litre?

1,000 mL.

Metric conversion: How many decilitres (dL) are in 1 L?

10 dL.

Metric conversion: How many centilitres (cL) are in 1 dL?

10 cL.

Metric conversion: How many millilitres are in 1 cL?

10 mL.

Metric conversion: Convert 2.5 kg to g.

2,500 g (2.5 × 1,000).

Metric conversion: Convert 1,750 mg to g.

1.75 g (1,750 ÷ 1,000).

Metric conversion: Convert 0.006 g to mg.

6 mg (0.006 × 1,000).

Metric conversion: Convert 1,250 mcg to mg.

1.25 mg (1,250 ÷ 1,000).

Metric conversion: Convert 0.75 L to mL.

750 mL.

Metric conversion: Convert 325 mL to L.

0.325 L.

Metric conversion: Convert 7.5 dL to mL.

750 mL (7.5 dL = 0.75 L).

Metric conversion: Convert 25 cL to mL.

250 mL.

Metric volumes: How many cubic centimetres (cm³) are in 1 mL?

Exactly 1 cm³ = 1 mL. The older abbreviation cc also refers to cm³, but mL is preferred for medicine volumes.

Metric volumes: How many cubic millimetres (mm³) are in 1 cm³?

1,000 mm³.

Metric volumes: How many cubic centimetres (cm³) are in 1 dm³?

1,000 cm³.

Metric volumes: How many cubic decimetres (dm³) are in 1 m³?

1,000 dm³.

Metric volumes: What is 1 dm³ in litres?

1 L (equivalent to 1,000 mL).

Metric volumes: What is 1 m³ in litres?

1,000 L.

Medication units: What is an insulin dose measured in?

Units of insulin, not simply mL; the volume needed depends on the product's concentration.

Medication safety: Is the abbreviation U recommended for medication orders?

No. Write out “units”; the abbreviation U can be misread as a zero or another numeral.

Conversions: What is dimensional analysis?

Multiplying by equal-value conversion ratios so unwanted units cancel, leaving the requested unit.

Conversions: What is the rule for converting a larger metric unit into a smaller one?

Multiply by the appropriate power of 10 (for example, 1.2 L × 1,000 mL/L = 1,200 mL).

Conversions: What is the rule for converting a smaller metric unit into a larger one?

Divide by the appropriate power of 10 (for example, 250 mg ÷ 1,000 = 0.25 g).

Apothecaries': What is the apothecaries' system?

A historical system for measuring medication mass and volume that uses units such as grain, dram, ounce, and minim.

Apothecaries': What does gr stand for?

Grain, a historical unit of mass; it is not the same abbreviation as g (gram).

Apothecaries': What does dr stand for in the historical weight table?

Dram, a historical unit of mass (not fluid dram).

Apothecaries': How many grains are in 1 apothecaries' dram?

60 grains.

Apothecaries': How many apothecaries' drams are in 1 apothecaries' ounce?

8 drams.

Apothecaries': How many grains are in 1 apothecaries' ounce?

480 grains (8 × 60).

Apothecaries': How many ounces are in the historical apothecaries' pound?

12 apothecaries' ounces, not 16. The slide's 16-oz figure belongs to the ordinary avoirdupois pound.

Ordinary weight: How many ounces are in an avoirdupois pound (lb)?

16 avoirdupois ounces.

Historical weight: Why should you distinguish apothecaries' and ordinary pounds?

Their ounce and pound definitions differ; mixing the systems creates incorrect conversions.

Historical weight: Approximately how many milligrams are in 1 grain?

1 gr = 64.79891 mg (about 64.8 mg). The slides use a rough 60 mg/gr conversion for classroom problems.

Historical weight: Approximately how many grains equal 1 gram?

About 15.43 grains; the slide rounds to approximately 15 grains.

Historical weight: If a textbook problem explicitly assumes 1 grain ≈ 60 mg, what is 2 grains?

Approximately 120 mg using that classroom approximation. It is not an exact conversion for real medication dosing.

Apothecaries' volume: What does fl oz mean?

Fluid ounce, a measure of volume, unlike oz when used for mass.

Apothecaries' volume: What does fl dr mean?

Fluid dram, a historical unit of volume, distinct from the dram of mass.

Apothecaries' volume: What is a minim (historically symbolized M)?

A small historical unit of liquid volume equal to 1/60 of a fluid dram.

Apothecaries' volume: How many US quarts are in 1 US gallon?

4 qt.

Apothecaries' volume: How many US pints are in 1 US quart?

2 pt.

Apothecaries' volume: How many US fluid ounces are in 1 US pint?

16 fl oz.

Apothecaries' volume: How many fluid drams are in 1 US fluid ounce?

8 fl dr.

Apothecaries' volume: How many minims are in 1 fluid dram?

60 minims.

Apothecaries' volume: Approximately how many mL are in 1 US gallon?

3,785 mL (3.785 L); the module rounds this to about 4,000 mL for its table.

Apothecaries' volume: Approximately how many mL are in 1 US quart?

946 mL; the module rounds this to about 1,000 mL.

Apothecaries' volume: Approximately how many mL are in 1 US pint?

473 mL; the module rounds this to about 500 mL.

Apothecaries' volume: What is 1 US fluid ounce in mL?

Approximately 29.57 mL, often rounded to 30 mL in classroom conversion tables.

Apothecaries' volume: What is 1 US fluid dram in mL?

Approximately 3.70 mL (29.57 ÷ 8).

Apothecaries' volume: About how many mL are in half a US fluid ounce?

About 14.8 mL, often rounded to 15 mL in the module.

Apothecaries' volume: Approximately how many mL are in 1 minim?

About 0.0616 mL (one-sixtieth of a US fluid dram).

Apothecaries' volume: How many minims per mL does the slide's rounded table suggest?

About 15 minims/mL in the slide's approximate table; the more precise US customary conversion is about 16.23 minims/mL.

Apothecaries' volume: Is 1 fluid ounce automatically equal to 1 ounce by mass?

No. Fluid ounces measure volume, while ounces measure mass; the slide's apparent equality should not be used for general conversions.

Apothecaries' volume: Is 1 fluid dram automatically equal to 1 dram by mass?

No. Fluid dram is volume; dram is mass.

Drops: Is there a universal number of drops (gtt) per mL for medication delivery?

No. Drop size depends on the device; for IV calculations use the administration set's stated drop factor rather than a universal drops-per-mL assumption.

Drops: What older classroom approximation appears in the slide table?

Approximately 15 drops per mL. Treat this as an exam-table approximation only, not a universal medication rule.

Household system: What kinds of measures does it use?

Cups, glasses, teaspoons, tablespoons, and similar household containers or utensils.

Household system: Why can household measuring utensils be inaccurate?

Actual glasses and eating spoons vary in capacity, unlike calibrated measuring devices.

Household conversion: What is the standard classroom equivalent of 1 teaspoon (tsp)?

5 mL when using a calibrated measuring teaspoon.

Household conversion: What is the standard classroom equivalent of 1 tablespoon (tbsp)?

15 mL when using a calibrated measuring tablespoon.

Household conversion: How many teaspoons are in 1 tablespoon?

3 teaspoons.

Household conversion: Approximately how many mL are in 1 US fluid ounce?

30 mL (more precisely, about 29.57 mL).

Household conversion: Approximately how many US fluid ounces are in 1 cup?

8 US fl oz per US customary cup.

Household conversion: What cup conversion does the module use?

1 cup ≈ 240 mL. This is an approximate US-style classroom value; a metric cooking cup may be 250 mL.

Household conversion: How many mL are in 2 cups using the module's 240-mL cup?

Approximately 480 mL (2 × 240).

Household conversion: Convert 10 mL into calibrated teaspoons using 5 mL/tsp.

2 teaspoons mathematically. For medicine, use a calibrated mL oral syringe or device, not an eating teaspoon.

Household conversion: How many tablespoons equal 30 mL using 15 mL/tbsp?

2 tablespoons.

Household practice: A problem defines 1 glass as 8 fluid ounces. How many glasses equal 24 fluid ounces?

3 glasses (24 ÷ 8). A real-world glass is not a fixed volume.

Household practice: Approximately how many mL are in 24 US fluid ounces using 30 mL/fl oz?

Approximately 720 mL. Using the more precise 29.57 mL/fl oz gives about 710 mL.

Household safety: What should be used instead of a regular kitchen spoon to measure oral liquid medicine?

An appropriate, calibrated dosing device marked in mL, such as an oral syringe.

Intake and output: What is intake and output (I&O) monitoring?

Recording volumes of fluid entering and leaving the body to assess fluid balance.

Intake and output: In what unit are clinical fluid volumes commonly recorded?

Millilitres (mL).

Intake and output: Give three examples of measurable intake.

Drinking liquids, IV fluids, and liquid tube feeds, according to local charting policy.

Intake and output: Give three examples of measurable output.

Urine, vomit (emesis), and measured drainage.

Intake and output: Why record fluids taken with a patient's meal tray?

Drinks and other countable liquid portions contribute to total oral fluid intake.

Intake and output: How do you calculate total recorded intake?

Add all measurable intake volumes over the charting interval, using mL.

Intake and output: How do you calculate total recorded output?

Add all measurable output volumes over the charting interval, using mL.

Intake and output: What is net recorded fluid balance?

Total measured intake minus total measured output.

Intake and output: What does a positive recorded fluid balance mean?

Measured intake exceeds measured output over that interval; it does not alone prove abnormal fluid retention.

Intake and output: What does a negative recorded fluid balance mean?

Measured output exceeds measured intake over that interval; interpret it with clinical context.

Intake practice: A patient drinks 250 mL water, 120 mL juice, and 180 mL soup. What is oral intake?

550 mL (250 + 120 + 180).

Output practice: Urine volumes are 300 mL, 200 mL, and 150 mL. What is total output?

650 mL.

Fluid balance practice: Intake is 1,600 mL and measured output is 1,100 mL. What is net recorded balance?

+500 mL (1,600 - 1,100).

Fluid balance practice: Intake is 950 mL and measured output is 1,200 mL. What is net recorded balance?

-250 mL.

Fluid balance: Why is a measured I&O total not a complete accounting of all fluid gain or loss?

Unmeasured losses, such as evaporation from skin and breathing, may not be captured in routine I&O totals.

Temperature: Which two scales are covered in the module?

Degrees Celsius (°C) and degrees Fahrenheit (°F).

Temperature: What is the formula to convert °F to °C?

°C = (°F - 32) ÷ 1.8, equivalent to (°F - 32) × 5/9.