🧮 Laboratory Math Review for the MedTech Board Exam

What the Laboratory Math course covers

1. Unit 1: Numbers & Units

   Significant figures, powers of ten, logs and pH, metric prefixes, English units and temperature.

   Significant figures · Powers of ten, logs & pH · Metric & SI units · English units, temperature & time

2. Unit 2: Reagents & Solutions

   Reagent water, chemical grades, making percent and molar solutions, normality, pH and concentrated reagents.

   Reagent water & chemical grades · Making percent & molar solutions · Equivalents & normality · pH, buffers & concentrated reagents

3. Unit 3: Dilutions & Lab Formulas

   Diluting stocks and samples, serial dilutions and titers, unknowns from standards, enzyme rates, unit conversions and clearance.

   Diluting stocks & samples · Serial dilutions & titers · Unknowns from standards · Enzyme rates, conversions & clearance

Sample Laboratory Math board exam questions

A few practice questions from the course, with explanations. Thousands more are in the app.

1. 1. How many significant figures are in 1.0040?

   1. 3
   2. 4
   3. 5
   4. 2
   Show answer

   Answer: C. 5

   Rules: nonzero digits count; zeros between them count; trailing zeros after a decimal point count; leading zeros never count. In 1.0040: 1, 0, 0, 4 and the final 0 all count = 5 significant figures.

2. 2. Which purification step mainly removes dissolved organic compounds and chlorine?

   1. 0.2 µm filtration
   2. Deionization
   3. Activated carbon
   4. Ion-exchange softening
   Show answer

   Answer: C. Activated carbon

   Activated carbon adsorbs dissolved organic compounds and chlorine. Deionization (ion exchange) removes charged ions only; a 0.2 µm filter removes bacteria and particles.

3. 3. 50 µL of serum is mixed with 450 µL of diluent. The dilution is:

   1. 1:5
   2. 1:10
   3. 1:9
   4. 1:450
   Show answer

   Answer: B. 1:10

   Dilution = sample volume ÷ total volume = 50 ÷ (50 + 450) = 50 ÷ 500 = 1/10, a 1:10 dilution. It is not 1:9: count the total, not just the diluent.

4. 4. 4.56 × 1.4 = ? (correct significant figures)

   1. 6
   2. 6.38
   3. 6.384
   4. 6.4
   Show answer

   Answer: D. 6.4

   In multiplication and division, the answer keeps as many significant figures as the least precise number. 1.4 has 2, so 4.56 × 1.4 = 6.384 is rounded to 2 figures: 6.4.

5. 5. The resistivity meter on the lab’s water system falls from 15 to 2 MΩ·cm. The most likely cause is:

   1. Too few bacteria
   2. Exhausted deionizer resin letting ions through
   3. A cold room
   4. Water that is too pure
   Show answer

   Answer: B. Exhausted deionizer resin letting ions through

   Resistivity measures how strongly water resists current; ions lower it. Type I water is about 10–18 MΩ·cm. A drop to 2 MΩ·cm means the deionizer resin is exhausted and ions are passing through.

6. 6. To make 2 mL of a 1:20 dilution, combine:

   1. 0.1 mL sample + 2.0 mL diluent
   2. 1 mL sample + 20 mL diluent
   3. 0.1 mL sample + 1.9 mL diluent
   4. 0.2 mL sample + 1.8 mL diluent
   Show answer

   Answer: C. 0.1 mL sample + 1.9 mL diluent

   Sample volume = total ÷ dilution = 2 mL ÷ 20 = 0.1 mL. Diluent = 2.0 − 0.1 = 1.9 mL. Adding 2.0 mL diluent would make a 1:21.

7. 7. 25.0 − 1.234 = ? (correct significant figures)

   1. 23.766
   2. 23.8
   3. 23.77
   4. 24
   Show answer

   Answer: B. 23.8

   In addition and subtraction, keep as many decimal places as the number with the fewest. 25.0 has one decimal place, so 25.0 − 1.234 = 23.766 rounds to 23.8.

8. 8. The final step that removes bacteria and particles from reagent water is usually:

   1. Storage in glass
   2. A 0.2 µm membrane filter
   3. Deionization
   4. Activated carbon
   Show answer

   Answer: B. A 0.2 µm membrane filter

   A 0.2 µm membrane filter at the end of the system traps bacteria and fine particles. Earlier steps (carbon, reverse osmosis, deionization) remove organics and ions.

Practice more Laboratory Math questions

How you review in MedTech Reviewer

• Learning path: short lessons, each followed by questions, with a checkpoint at the end of every unit.
• Spaced repetition: questions you miss come back sooner, so key facts stick for exam day.
• Flashcards and timed quizzes in exam style, with an explanation for every answer.
• Board-readiness score per subject, so you know where to focus.
• Arcade games, PvP battles and Guilds to keep reviewing fun with classmates.

Other MedTech subjects

🩸 Hematology 🩹 Coagulation ⚗️ Clinical Chemistry 🧪 Urinalysis & Body Fluids 💉 Blood Banking 🛡️ Immunology & Serology 🦠 Microbiology 🪱 Parasitology, Mycology & Virology 🧬 Molecular Diagnostics 📋 Laboratory Management