NSG 501 Exam 3: Medication Dosage Calculations MASTERY – NCLEX-Aligned Practice, IV Drip Rates & Expert Strategies (Instant Download)"with complete verified solutions 2025

medication math

converting and doing math to get the right dose for a patient

key points to medication math

>>Always double-check your work

>>Make sure you have the right units

>>Know your conversion factors

>>You are the final check before the patient*!!*

as nurses we need to know how to:

-do basic math

-need to check EPIC, MAR and what the pt dose is

should there be a trailing 0 after a decimal?

no!

No trailing zero after a decimal point or a whole number

1 mg (not 1.0 mg)

should there be a "naked" decimal point ( .4) ?

no!

No naked decimal point

0.5 ml (not .5 ml)

should there be a terminal period after units are listed?

no!

Use mg, ml, g, without a terminal period.

->Period could be mistaken as number 1 if written poorly.

mg (not mg.)

should there be a space between the number and the units? (10mg or 10 mg)

Numerical dose and unit of measure

>> Place adequate space between the dose and the unit of measure

10 mg (not 10mg)

should commas be used for # above 1,000?

yes, Use commas for dosing units at or above 1,000

can you use abbreviations?

Use only approved abbreviations

>do not want to confuse others

>we want to speak in a common language

unsafe abbreviations

many abbreviations you should NOT use

rules of rounding

> or = to 5 round up

<5 round down

Never round up medication in tablet form

--> 1.5 tablets remains as is; not 2 tablets

Each step of calculation must be carried out to at least the hundredth place

>aka do not round as you go, you can only round the final answer

->The final step or "final answer" is to be rounded:

>Tenths if greater than 1 (1.56 = 1.6)

>Hundredths is less than 1 (0.422 = 0.42)

medication math is all about getting the right answer of math problem T/F

no because it hold more value than just the right answer to the problem

-yes we need right answer

-but we also need to understand the importance of the correct dose!

dosage calculation conversions

you need to know/memorize these conversions

1 mg

1000 mcg

1g

1000 mg

1L

1000 mL

1 mL

1 cc

5 mL

1 Tsp

3 Tsp

1 tbsp

15 mL

1 tbsp

30 mL

1 oz

1 oz

2 tbsp

8 oz

1 cup

1kg

1000 grams (g) (gm)

1 kg

2.2 lbs

unit conversion

The process of changing a measure to an equivalent measure that has different units.

example: 1kg = 2.2 lbs

to convert from pounds to kg

# pounds / 2.2 = # of kg

To convert kilograms to pounds:

# of kg. x 2.2 = # of lbs.

If your patient weighs 140 lbs., how many kg. does he weigh?

140/2.2 = 63.63 kg (rounded to 63.6 kg)

If your patient weighs 92.4 kg., how many pounds does he weigh?

92.4 kg. x 2.2 = 203.28 lbs. (rounded to 203.3)

3 methods to med math

Formula method

Ratio proportion method

Dimensional analysis

formula method

Dose ordered x Quantity on hand /

Dose on Hand = amount to administer

Example: Patient to be given 60 mg of toradol IM. The vial of toradol contains 30mg/1mL. How many mililiters will you administer?

Dose ordered: 60mg

Quantity on hand: 1mL

Dose on Hand: 30mg

60mg x 1mL = 2 mL to be administered

30mg

ratio proportion method

Set up ratios that are equal to one another and cross-multiply to solve

dose ordered / amt to administer = dose on hand / quantity on hand

Ex: Example: Patient to be given 60 mg of toradol IM. The vial of toradol contains 30mg/1mL. How many milliliters will you administer?

Dose ordered: 60mg

Quantity on hand: 1mL

Dose on Hand: 30mg

60mg/ x mL = 30 mg / 1 mL = 30x =60 = x= 2 mL

dimensional analysis method

a method of problem solving whereby problems are set up so that unwanted units cancel

Dose ordered x concentration on hand

Allows for all math to be completed in one linear setup by matching up units to cancel out

Example: Patient to be given 60 mg of toradol IM. The vial of toradol contains 30mg/1mL. How many mililiters will you administer?

Dose ordered: 60mg

Concentration: 30mg/1mL

60mg x 1mL/30mg= 2 mL

A client is ordered 50 mg of gentamicin (Garamycin) by IM injection. The drug is available in 20 mg/5 mL. How many mL should the nurse administer?

Answer: 12.5 mL

The doctor has ordered Solu-Medrol, 30mg IVP q8h for a patient with a COPD exacerbation. The vial comes as 150mg/2ml. How many ml will you give over 24 hours?

1.2 mL over 24 hours

Physician orders lasix 4mg/kg/day to be given q6 hours. Patient weighs 22 lbs and lasix comes in vials as 5mg/2mL. How many mL will you administer per dose?

4 mL/dose

infusion rates

formula:

total volume in mL / # of hours

ml per hour

example:

1000ml / 8 hrs

= 125 ml / hr

A doctor has ordered a 1.5L NS bolus to infuse over 2hours. What ml/hr will you set the pump to infuse this fluid?

750 ml/hour

for all these problems , where can i see the work?

the work for these problems is in the med math lecture

>lists steps for each method on solving!