FREE NCLEX-RN PRACTICE
Medication Math Practice: Match Units Before You Calculate
Medication math is a units task before it is an arithmetic task. Read the order, label the units, convert only when needed, and calculate after the order and supply use the same unit. These public teaching examples are separate from protected prediction reports and are not patient-specific dosing advice.
Use the worked feedback to notice the pattern: convert first, set up the relationship, calculate, then pause for a medication-safety check. In clinical care, follow local policy, use required independent checks, and clarify any order or result that does not make sense.
WORK THROUGH THE ARITHMETIC
Practice dose-to-volume calculations
Use the same mass unit for both amounts. This tool shows the arithmetic for study examples; it does not select a medicine or a clinical dose.
Practice the skill, then review the reasoning
An order is for 0.35 mg. A vial contains 175 mcg/mL. How many mL are needed? Enter the number only.
An IV order is 1,200 mL over 10 hours. Which pump setting is correct?
A client weighs 132 lb. An order is for 4 mg/kg per dose. Use 2.2 lb = 1 kg. How many mg are needed per dose? Enter the number only.
1. Match the units before using the concentration
A medication label may use mg/mL while an order uses mcg or g. Convert until both use the same mass unit. The core relationships are 1 g = 1,000 mg and 1 mg = 1,000 mcg.
For example, 0.6 mg is 600 mcg. If a solution contains 200 mcg/mL, divide 600 mcg by 200 mcg/mL to get 3 mL. The units cancel to mL, which is the volume to measure.
2. Use the label as a dose-to-volume relationship
A liquid label such as 125 mg in 5 mL states both the medication amount and the volume that holds it. Keep that pair together. If the ordered dose is 250 mg, it is twice the labeled amount, so the volume is twice 5 mL, or 10 mL.
Use an oral syringe or another calibrated device whose markings match the ordered unit. Household spoons vary in volume and should not be used to measure a medication dose.
3. Convert weight and time deliberately
Weight-based orders require kilograms. Convert pounds to kilograms by dividing pounds by 2.2, then multiply by the ordered mg/kg dose. Keep each line visible so it is easy to spot a misplaced decimal or unit.
For an IV pump rate, divide total volume in mL by time in hours. For gravity tubing, multiply mL by the drop factor in gtt/mL, divide by minutes, and round only the final drops-per-minute setting.
4. Calculation is followed by a safety pause
A correct calculation is only one part of safe administration. Before preparing a medication, confirm the client, medication, dose, route, time, allergies, relevant assessment findings, and required policy checks. If the order, concentration, or result is unclear, stop and clarify.
These exercises are public teaching examples. They do not provide treatment instructions for an individual client and do not convert performance into an official score or a pass guarantee.
Questions about this practice
Why do I convert before calculating?
A concentration only works when its medication unit matches the ordered unit. Converting first prevents mixing mg, mcg, and g in the same setup.
Can I use a kitchen teaspoon for a liquid dose?
No. Household spoons vary. Use a calibrated oral syringe, cup, or other device with units that match the prescribed dose.
When should I round a gravity drip rate?
Keep precision through the setup and round only the final gtt/min answer to a whole drop. Follow local policy for any required rounding convention.
Do these exercises predict an NCLEX result?
No. They are public practice examples for medication-math concepts, not an official score conversion, clinical order set, or guarantee of exam performance.
References
- MedlinePlus: Liquid medication administration
- NCSBN 2026 NCLEX-RN Test Plan
- AHRQ MATCH Toolkit for Medication Reconciliation
Updated October 25, 2026 · PassPredictor