Pharmacy math practice test: PTCB calculations and order entry

Order Entry and Processing is 22.5% of the 2026 PTCE, about 18 of the 80 scored questions, and it holds most of the exam's math: days' supply and quantity, doses by weight, concentrations and dilutions, percent strength, IV and drip rates, plus sig codes, NDC numbers, DAW codes and expiration dates. The free drill below has 12 questions with every calculation worked.

22.5%
of the 2026 PTCE: 20
questions in our mock: 17
question types generated: 12
questions in the free drill

Last checked 22 October 2026 · Domain weight from ptcb.org; alligations are no longer tested from 2026

Free pharmacy math drill: 12 original PTCB-style questions at the real exam's pace, then every answer worked step by step. No sign-up.

12
questions
14:40
time limit
Free
every answer explained

By the LifeScore Editorial Team · Updated 22 October 2026 · How we check facts · How this is scored

What math is on the PTCB exam?

Practical dispensing math: days' supply and quantity, doses from a concentration, doses by body weight, percent and ratio strength, dilutions, IV flow and drip rates, and unit conversions. From 2026, alligations are no longer on the outline.

The calculation types and how to set each up
Type	Set it up as
Days' supply	Quantity ÷ amount used per day
Quantity	Amount per dose × doses per day × days
Dose from a concentration	Dose wanted ÷ strength × volume (e.g. mg ÷ mg per 5 mL × 5 mL)
Dose by weight	Convert lb to kg (÷ 2.2), then mg/kg × kg, then divide by doses per day
Percent strength (w/v)	Grams per 100 mL
Ratio strength	1:1,000 means 1 g in 1,000 mL
Dilution	C1 × V1 = C2 × V2
IV rate	Volume ÷ hours = mL/hr
Drip rate	Volume ÷ minutes × drops per mL = gtt/min

An on-screen calculator is provided, so the arithmetic is rarely the problem. Points go on the setup: a missing conversion, a dose per day used as a dose per dose, or an answer in the wrong unit. Write the unit on every number and cancel them; if the units left over are not what the question asks for, the setup is wrong.

How do you calculate days' supply?

Divide the quantity dispensed by the amount the patient uses each day. 60 tablets taken twice a day is a 30-day supply; a taper is added step by step.

Read the sig first and turn it into a number per day: bid is 2, tid is 3, qid is 4, q6h is 4, q8h is 3, q12h is 2. For liquids, multiply the dose in mL by the doses per day and divide the bottle volume by that. For inhalers, divide the puffs in the canister by the puffs a day. For insulin, divide the total units in the pens or vials by the units a day.

An inflated days' supply makes the next fill reject as too soon; a short one can trigger an audit. Billing the right days' supply is part of the same domain.

PTCB-style question 1 · Quantity
A prednisone 10 mg taper reads: 4 tablets daily for 3 days, then 3 daily for 3 days, then 2 daily for 3 days, then 1 daily for 3 days. How many tablets should be dispensed?
1. A30
2. B40
3. C12
4. D24
Worked answer
A: 30. Add each step: 4 × 3 = 12, 3 × 3 = 9, 2 × 3 = 6 and 1 × 3 = 3. 12 + 9 + 6 + 3 = 30 tablets, for a 12-day supply.
1. 4 × 3 = 12
2. 3 × 3 = 9; 2 × 3 = 6; 1 × 3 = 3
3. 12 + 9 + 6 + 3 = 30 tablets
The trap: Answering 12, the number of days. The question asks for tablets.

How do you calculate a dose by weight?

Convert pounds to kilograms by dividing by 2.2, multiply by the mg/kg dose, divide by the number of doses if the order is per day, then convert milligrams to milliliters with the concentration.

Conversions to know
Unit	Equals
1 kg	2.2 lb
1 teaspoon (tsp)	5 mL
1 tablespoon (tbsp)	15 mL
1 fluid ounce	30 mL (29.57 mL exactly)
1 g	1,000 mg
1 mg	1,000 mcg
1 L	1,000 mL
Drops	20 drops per mL unless the dropper says otherwise

PTCB-style question 1 · Weight-based doses
A child weighs 44 lb. Amoxicillin is ordered at 40 mg/kg/day, divided every 12 hours. The suspension is 400 mg/5 mL. How many mL is each dose?
1. A5 mL
2. B10 mL
3. C2.5 mL
4. D11 mL
Worked answer
A: 5 mL. 44 lb ÷ 2.2 = 20 kg. 40 mg × 20 kg = 800 mg a day, given as two doses of 400 mg. At 400 mg per 5 mL, each dose is 5 mL.
1. 44 lb ÷ 2.2 = 20 kg
2. 40 mg/kg/day × 20 kg = 800 mg/day; ÷ 2 doses = 400 mg
3. 400 mg ÷ 400 mg × 5 mL = 5 mL
The trap: Using pounds as kilograms: 40 × 44 = 1,760 mg a day gives 11 mL a dose, more than double the right amount.
PTCB-style question 2 · Percent strength
How many grams of dextrose are in 250 mL of D5W (5% dextrose in water)?
1. A12.5 g
2. B5 g
3. C25 g
4. D1.25 g
Show the worked answer
A: 12.5 g. A 5% weight-in-volume solution has 5 g per 100 mL. 250 mL ÷ 100 × 5 g = 12.5 g.
1. 5% w/v = 5 g in every 100 mL.
2. 250 mL is 2.5 × 100 mL.
3. 2.5 × 5 g = 12.5 g
The trap: Answering 5 g, the amount in 100 mL, not in 250 mL.

The most expensive slip is using pounds as kilograms, which more than doubles the dose. Check every answer for sense: a 20 kg child should not get an adult dose.

New numbers in every drill

Eight full mocks and four order entry drills, with every calculation generated fresh and worked step by step.

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Prep courses for these tests usually cost $19 to $129. The PTCB Pass Pack is US$39 (£29), once.

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How do you calculate an IV flow rate?

For mL per hour, divide the volume by the hours. For drops per minute, divide the volume by the minutes and multiply by the set's drops per mL (the drop factor).

PTCB-style question 1 · IV rates
An order is for 1,000 mL of normal saline over 8 hours. What is the rate in mL per hour?
1. A125 mL/hr
2. B150 mL/hr
3. C100 mL/hr
4. D80 mL/hr
Show the worked answer
A: 125 mL/hr. Rate equals volume divided by time: 1,000 mL ÷ 8 hours = 125 mL per hour.
1. Volume: 1,000 mL. Time: 8 hours.
2. 1,000 ÷ 8 = 125
3. 125 mL/hr
The trap: Dividing by minutes when the question asks for hours.
PTCB-style question 2 · Drip rates
500 mL is to run over 4 hours using a set that delivers 20 drops per mL. About how many drops per minute is that?
1. A42
2. B125
3. C21
4. D83
Worked answer
A: 42. 4 hours is 240 minutes. 500 mL ÷ 240 min = 2.08 mL per minute, and 2.08 × 20 drops = 41.7, or about 42 drops per minute.
1. 4 hours × 60 = 240 minutes
2. 500 mL ÷ 240 = 2.083 mL/min
3. 2.083 × 20 = 41.7, about 42 gtt/min
The trap: Answering 125, the rate in mL per hour, instead of converting to drops per minute.

Infusion time questions run the other way: hours = volume ÷ rate. A 1,000 mL bag at 125 mL/hr lasts 8 hours; started at 8:00 a.m., it finishes at 4:00 p.m. Read whether the question asks for a duration or a clock time.

What order entry topics are on the PTCB exam?

Translating sig codes, reading NDC and lot numbers, converting NDCs to the 11-digit billing format, expiration and beyond-use dates, DAW codes, prior authorizations and rejected claims, and the supplies that go with a prescription.

Common sig codes
Code	Meaning
po	by mouth
sl	under the tongue
bid / tid / qid	twice / three times / four times a day
q6h	every 6 hours
qhs	at bedtime
prn	as needed
ac / pc	before / after meals
gtt	drop(s)
ut dict	as directed

NDC: labeler, product and package segments. The 11-digit billing format is 5-4-2; add a leading zero to whichever segment is short.
Expiration: a date with only a month and year runs to the last day of that month.
DAW 0: substitution allowed. DAW 1: the prescriber requires the brand. DAW 2: substitution allowed, the patient asks for the brand.
A prior authorization reject goes to the prescriber for clinical information, through the pharmacist; never change the NDC or days' supply to make a claim pay.

PTCB-style question 1 · NDC numbers
A package shows the 10-digit NDC 12345-678-90 (5-3-2 format). What is the 11-digit NDC used for billing?
1. A12345-0678-90
2. B12345-678-090
3. C01234-5678-90
4. D12345-6789-00
Worked answer
A: 12345-0678-90. Billing uses a 5-4-2 format. A 5-3-2 NDC needs a leading zero in the middle (product) segment: 12345-0678-90.
1. Target format: 5-4-2.
2. The labeler (5) and package (2) segments already fit.
3. The product segment has 3 digits, so add a zero in front: 0678.
The trap: Adding the zero to the wrong segment. The zero goes in front of whichever segment is short.

Practise the whole domain in the free drill above, then take the full PTCB practice test. The study plan in how to pass the PTCB spaces the math out so it sticks, and more worked questions are on PTCB sample questions.

Frequently asked questions

Is there a calculator on the PTCB exam?

Yes. An on-screen calculator is provided. You cannot bring your own.

Are alligations on the 2026 PTCB?

No. The 2026 outline removed alligation calculations along with nonsterile compounding.

How many math questions are on the PTCB?

PTCB does not publish a count. Most calculations sit in Order Entry and Processing, 22.5% of the exam, with a few in other domains.

What is the most common pharmacy math mistake?

Using pounds as kilograms in a weight-based dose. Convert first: divide pounds by 2.2.

Are these real PTCB questions?

No. They are original PTCB-style questions with computed keys. LifeScore is not affiliated with PTCB.

Make the math your safest points

Eight full PTCB-style mocks and four drills per domain, every calculation worked, for one payment.