Dosage calculation questions are some of the most predictable — and most learnable — problems on the TEAS 7 Math section. Yet students consistently lose points here because they learned the wrong method. Here's the one method that works every time.
The Ratio-Proportion Method
Every dosage calculation question can be solved with one setup: known ratio = unknown ratio. Set up two fractions equal to each other, cross-multiply, and solve for x.
(Have / Volume on hand) = (Desired dose / Volume to give)
Rearranged: Volume to give = (Desired dose × Volume on hand) / Have
Worked Example 1 — Tablet Dosage
A patient needs 500 mg of amoxicillin. Tablets available are 250 mg each. How many tablets should be given?
Desired = 500 mg
Tablets = 500 ÷ 250 = 2 tablets
Worked Example 2 — Liquid Medication
A medication label reads 250 mg per 5 mL. The order is for 650 mg. How many mL should be given?
Cross multiply: 250x = 650 × 5 = 3,250
x = 3,250 ÷ 250 = 13 mL
Worked Example 3 — Weight-Based Dosing
A drug is ordered at 0.5 mg/kg for a 68 kg patient. Maximum dose is 30 mg. What dose should be given?
34 mg exceeds the 30 mg maximum
Give: 30 mg (the maximum allowed dose)
💡 Always check the maximum dose. TEAS 7 questions deliberately include a cap — missing it is one of the most common errors.
IV Drip Rate Calculations
Some TEAS 7 questions involve calculating drip rates. The formula is:
Example: 1,000 mL over 8 hours = 125 mL/hr
Practice Strategy
- Write out the ratio-proportion setup for every problem — don't do it in your head
- Always label your units (mg, mL, kg) throughout the calculation
- Check your answer makes logical sense (would a nurse really give 50 tablets?)
- Do at least 20 practice problems before the exam
You can also practice these types of problems in our free TEAS 7 practice quiz — the Math section includes dosage calc and ratio questions.
Want One-on-One TEAS 7 Math Help?
Our tutors walk through dosage calculations step by step until they click — guaranteed.
Book a Free Consultation