Dosage calculation test practice

What the real test usually looks like

There is no single dosage calculation test. Each nursing program writes its own medication math exam, often called a dosage calculation, med math or medication calculation test, and sets its own length, time limit, required score and rules. Your syllabus or student handbook is the best guide to yours. Four public school policies show the range:

• Mercer County Community College: 20 fill-in-the-blank questions in 60 minutes, given in every clinical course within the first two weeks of clinical (MCCC).
• Valdosta State University: 10 to 20 dosage calculation questions, computer-based, covering medication dosage and IV fluid calculations, given each semester in a designated clinical course (Valdosta State).
• Shawnee State University: a dosage calculation exam in selected nursing courses, with only instructor-provided calculators and set rules for decimals, units and rounding (Shawnee State).
• Ogeechee Technical College: a medication calculation exam each semester that must be passed before any medication administration in clinical (Ogeechee Tech).

Rules many programs use. Shawnee State's posted policy is a clear example (Shawnee State):

• A zero always before a decimal point, never after it: write 0.5 mg, never .5 mg; write 5 mg, never 5.0 mg.
• Every answer labeled with its unit. An unlabeled answer is marked wrong.
• Rounding: an answer less than 1 to hundredths (0.6666 becomes 0.67), an answer greater than 1 to tenths (1.812 becomes 1.8), and drops to the nearest whole number.

Your school's rules may differ, so learn them before you practice.

What our mocks cover. Our full mocks are 20 questions in 60 minutes, in five sections in order: unit conversion (4), oral doses (5), IV flow rates (4), drip rates (3) and weight-based doses (4). Each answer is a number, and each question states the unit and the rounding rule. You can go back and flag questions, and a calculator is allowed. The free sample above gives four choices for each question. Every medicine and order is invented: this is math practice, never medical advice, and our score is not a program's pass mark. Check your own school's length, time, rules and required score.

Question types with worked examples

One worked example for each section, with the trap most people fall into. All medicines are invented.

1. Unit conversion. Convert 2,500 mcg to mg. 1 mg = 1,000 mcg, so divide: 2,500 / 1,000 = 2.5 mg. Trap: multiplying when going to a larger unit. Going from a smaller unit to a larger one, the number gets smaller.

2. Oral doses. Order: Drug G 75 mg. On hand: 50 mg per mL. Desired over have, times the volume: 75 / 50 x 1 = 1.5 mL. Trap: flipping the fraction. Always put the ordered dose on top.

3. IV flow rates. 500 mL over 4 hours by pump: 500 / 4 = 125 mL/h. Trap: leaving the time in minutes. Pumps are set in mL per hour.

4. Drip rates. 100 mL over 60 minutes with 20 gtt/mL tubing: 100 x 20 / 60 = 33.3, which rounds to 33 gtt/min. Trap: rounding drops to a decimal. You cannot count part of a drop, so drops are usually whole numbers.

5. Weight-based doses. Order: Drug H 5 mg/kg. Weight: 66 lb. 66 / 2.2 = 30 kg, and 5 x 30 = 150 mg. Trap: using pounds as kilograms. Check which unit the order uses, and convert the weight first.

How to prepare

1. Read your school's policy first. Find the number of questions, the time limit, the required score, the number of attempts and whether you may use your own calculator. Shawnee State, for example, allows only calculators provided by the instructors (Shawnee State).
2. Learn your school's rounding and labeling rules. Rounding to tenths where your school wants hundredths, or leaving off a unit, can make a correct calculation wrong.
3. Memorize the core conversions. 1 g = 1,000 mg, 1 mg = 1,000 mcg, 1 L = 1,000 mL, 1 kg = 2.2 lb, 1 h = 60 min.
4. Pick one method and use it every time. Desired over have times volume, ratio and proportion, and dimensional analysis all work. Switching methods under time pressure is where errors start.
5. Write every step with units. Units that cancel correctly show the setup is right before you calculate.
6. Check whether the answer makes sense. Ten tablets, or a pump rate of thousands of mL per hour, is a sign to recheck the setup.
7. Practice at the real pace. If your test is like Mercer County's, 20 questions in 60 minutes is 3 minutes a question (MCCC). Take full timed mocks so the pace feels normal on the day.

How scoring usually works

Each program sets its own required score, and it is usually high, because the test is about patient safety. Some public examples:

• Valdosta State: 90 percent or higher, with two attempts. A student who does not reach 90 percent on the second attempt must drop all clinical courses for that semester (Valdosta State).
• Shawnee State: a minimum of 90 percent, with up to three attempts (Shawnee State).
• Mercer County Community College: students who do not score 100 percent get a second attempt at a different version of the exam, and may review their incorrect answers from the first attempt (MCCC).
• Ogeechee Technical College: a minimum of 90 percent each semester, with up to three attempts in a semester and remediation between them (Ogeechee Tech).

Many programs mark an answer wrong if the unit is missing or the rounding rule is not followed, even when the setup is right.

Our practice score is the number of our own questions you answered correctly, with a breakdown by section, so you can see where to focus. It is a practice score: it is not any program's pass mark, and it does not predict whether you will pass. Your program sets the score it requires.

Common mistakes on dosage calculation tests

• Skipping the conversion. If the order is in grams and the label in milligrams, convert before you do anything else.
• Flipping the fraction. The ordered dose goes on top, the dose on hand underneath.
• Forgetting the volume. With a liquid, multiply by the volume on the label (per 5 mL, for example).
• Mixing up hours and minutes. Pump rates are mL per hour; drip rates are drops per minute.
• Rounding too early. Keep the full number until the last step, then round once by your school's rule.
• Leaving off the unit, or adding a trailing zero. Write 5 mL, not 5 or 5.0 mL; write 0.5 mg, not .5 mg.
• Using pounds as kilograms. Check the unit of the weight before a weight-based dose.

A one-week dosage calculation study plan

• Day 1: Take the free sample above. For each miss, note whether it was a conversion, a setup or a rounding slip.
• Day 2: Unit conversions: g, mg and mcg; L and mL; lb and kg; hours and minutes.
• Day 3: Oral doses: tablets and liquids, with a conversion in each problem.
• Day 4: IV flow rates and drip rates: mL/h for pumps, gtt/min for gravity tubing.
• Day 5: Weight-based doses: per dose and per day, divided doses.
• Day 6: Take a full timed mock. Review every explanation, right or wrong.
• Day 7: Rest, reread your school's rounding and labeling rules, and redo only the questions you missed.