| Course | HCA 105 Pharmacology |
|---|---|
| Module | Module 5 |
| Paper type | Dosage calculation paper |
| Length | About 1,058 words, 6 pages |
| Format | APA 7 student paper |
| School | Aspen University |
| Program | Health Care Administration |
| Updated | September 2026 |
Free sample paper for HCA 105 Module 5
Desired Over Have: Five Worked Dosage Calculations and the Checks That Go With Them
Student Name
Health Care Administration Program, Aspen University
HCA 105: Pharmacology
Instructor Name
Month Day, Year
Desired Over Have: Five Worked Dosage Calculations and the Checks That Go With Them
Dosage calculation turns an order into an amount to give. This paper explains the most common method, works through five examples written for teaching and shows the checks that should accompany every result. The examples are practice problems, not real orders, and the paper ends by clarifying what allied health workers may do with a calculated dose in practice.
The Desired-Over-Have Method
The most widely taught method divides the desired dose by the dose on hand and multiplies by the quantity that contains the dose on hand: desired divided by have, times quantity. If a provider orders 500 mg and the medicine comes as 250 mg in each 5 mL, the amount to give is 500 divided by 250, times 5 mL, which equals 10 mL. Before using the formula, the desired and on-hand doses must be in the same unit (Lilley et al., 2023).
Tablets
For tablets, the quantity is one tablet. An order for 25 mg, with 12.5 mg tablets available, gives 25 divided by 12.5, times 1 tablet, or 2 tablets. If a calculation produces an odd fraction such as 1.33 tablets, something is wrong: either the calculation or the tablet strength chosen. Tablets can be split only if scored and allowed for that drug, and capsules are never split.
Checking Against Usual Doses
A calculation can be arithmetically correct and still clinically wrong if the order itself contains an error, such as a misplaced decimal. Experienced staff compare the ordered dose with the usual range listed in a drug reference. An order for 100 mg of a drug usually given in 10 mg doses deserves a question to the provider before anything is prepared. Allied health workers are not expected to judge doses clinically, but noticing when an order looks very different from what is usual, and asking, is an important safety habit.
Oral Liquids and Injections
The same method applies to liquids. An order for 150 mg of a liquid supplied as 100 mg per 5 mL gives 150 divided by 100, times 5 mL, or 7.5 mL. For an injection, an order for 40 mg with 80 mg in each 2 mL vial gives 40 divided by 80, times 2 mL, or 1 mL. Liquids should be measured with an oral syringe or calibrated cup, not a household spoon. For injections, the calculated volume should also make sense for the route; an intramuscular volume of 8 mL, for example, would be far too large for a single adult site and signals an error.
A Weight-Based Pediatric Dose
Many children's doses are based on weight. Suppose a practice order reads 20 mg per kilogram per day, divided into two doses, for a child weighing 22 kg. The daily dose is 20 times 22, or 440 mg. Divided into two doses, each dose is 220 mg. If the liquid contains 200 mg per 5 mL, each dose is 220 divided by 200, times 5 mL, or 5.5 mL. Weight must be in kilograms; a weight recorded in pounds must be converted first, since using pounds would give more than twice the intended dose. A final sense check compares the answer with the child's size: 5.5 mL twice a day is a plausible volume for a young child, while 55 mL would signal a misplaced decimal.
Five Worked Problems
The table summarizes the worked problems with a quick check for each.
| Order (practice) | Available | Calculation | Answer | Check |
|---|---|---|---|---|
| 500 mg | 250 mg per 5 mL | 500 / 250 x 5 mL | 10 mL | Twice the concentration's dose, so twice 5 mL |
| 25 mg | 12.5 mg tablets | 25 / 12.5 x 1 | 2 tablets | Whole number of tablets |
| 150 mg | 100 mg per 5 mL | 150 / 100 x 5 mL | 7.5 mL | One and a half times 5 mL |
| 40 mg | 80 mg per 2 mL | 40 / 80 x 2 mL | 1 mL | Half the vial |
| 220 mg per dose | 200 mg per 5 mL | 220 / 200 x 5 mL | 5.5 mL | Slightly more than 5 mL |
Common Traps
Several traps recur. Mixing units, such as grams in the order and milligrams on the label, produces errors of a thousandfold. Using pounds in a weight-based formula more than doubles the dose. Confusing a daily dose with a single dose gives two or three times the intended amount. Misreading a concentration, such as 250 mg per 5 mL as 250 mg per mL, gives a fivefold error. Each trap is caught by writing units at every step and checking the size of the answer.
Documenting the Calculation
When a calculated dose is given, the record should show the dose in the ordered unit, the amount given and the concentration used, for example 220 mg given as 5.5 mL of a 200 mg per 5 mL suspension. This lets anyone reviewing the record confirm the calculation. For weight-based doses, the weight used and the date it was measured should also be recorded, since a weight from months ago may no longer be accurate for a growing child.
When to Ask for a Second Check
High-risk drugs, weight-based pediatric doses and any calculation that produces an unusual result deserve a second, independent check by another qualified person. Research suggests calculation is only one of several contributors to medication errors in practice (Wright, 2010), and anxiety about math can itself affect accuracy (Williams & Davis, 2016), so checking the label, the patient and the order matters as much as checking the arithmetic. Asking for a check is a sign of professionalism, not weakness.
The Allied Health Role
Allied health workers may calculate and prepare doses only as their training, state law and employer policy allow and as the supervising provider delegates. They do not change a dose, choose a dose or interpret an unclear order. When a calculation seems wrong, the right action is to stop and ask the nurse, pharmacist or provider before preparing anything.
Conclusion
The desired-over-have method, applied with matching units, handles tablets, liquids and injections, and weight-based dosing adds one step. Five worked examples show the method and its checks. The most important habits are writing units, estimating before calculating, watching for daily versus single doses and asking for a second check when the stakes or the doubts are high.
References
Lilley, L. L., Collins, S. R., & Snyder, J. S. (2023). Pharmacology and the nursing process (10th ed.). Elsevier.
Williams, B., & Davis, S. (2016). Maths anxiety and medication dosage calculation errors: A scoping review. Nurse Education in Practice, 20, 139-146. https://doi.org/10.1016/j.nepr.2016.08.005
Wright, K. (2010). Do calculation errors by nurses cause medication errors in clinical practice? A literature review. Nurse Education Today, 30(1), 85-97. https://doi.org/10.1016/j.nedt.2009.06.009
HCA 105 Module 5 instructions, in plain terms
Drug calculations appear in Aspen's catalog description of HCA 105, and this example takes its direction from that line, since the module wording itself is kept inside the course. A calculation assignment usually provides orders and available strengths and asks you to calculate amounts, show your method and explain your checks. Some instructors require a particular method, such as desired over have, ratio and proportion or dimensional analysis. Check which method is expected, how answers should be rounded, whether weight-based problems are included and whether you must explain errors to avoid. Write your own examples only if permitted and label them as practice. Some courses also ask you to identify which answers need a second person to check them.
How the HCA 105 Module 5 example is put together
About 1,045 words are organized under twelve headings, with one worked-problem table. The introduction explains what dosage calculation does. The method section states the formula and the unit rule. Tablets, then liquids and injections, are calculated with sense checks. A section compares results with usual doses, and a weight-based pediatric dose is worked in steps. The table summarizes five problems with checks. Common traps and documentation of the calculation follow, then when to ask for a second check, the allied health role and a conclusion listing the key habits. Each step in the worked examples shows its units. The last section returns to the role limits.
Where the marks sit in the HCA 105 Module 5 rubric
Calculation papers are commonly marked on correct answers, clear method, attention to units and safety habits. Every answer is correct and shown step by step. The unit rule is stated before the first example, which a margin note credits as preventing the most common error. The worked-problem table pairs each answer with a check, noted beside the table. A further note praises comparing orders with usual doses, since correct arithmetic can still produce an unsafe dose. Traps are named specifically. The role section keeps the paper within allied health scope. The textbook and two research reviews are cited where they support points. Clear layout, one step per line, also makes the answers easy for an instructor to follow.
HCA 105 Module 5 help from the desk
The most frequent mistake is starting a calculation before converting units, which produces errors of a thousandfold. Convert first. Students also use a child's weight in pounds, more than doubling the dose; convert to kilograms. Another common error is treating a daily dose as a single dose. Read the order carefully. Some papers show answers without checks, missing the chance to catch errors. Add a one-line check to each. Finally, do not present allied health workers as choosing or changing doses; show them calculating as delegated and asking when something looks wrong. If an answer is an odd fraction of a tablet, recheck the calculation before anything else.
Write yours, or have the desk draft it
This paper is an original model document written by our desk, not a submitted student paper and not an official Aspen University document. Read it for the moves, then write your own to the instructions in your classroom. If you want one built to your exact prompt and rubric, the first custom sample is free and arrives in 24 to 48 hours.
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HCA 105 Module 5 questions, answered
What does HCA 105 Module 5 usually ask for?
Aspen's HCA 105 description includes drug calculations, so a set of worked dosage calculations with explanations is a typical assignment. Check your classroom for the format.
What is the desired-over-have formula?
Desired dose divided by dose on hand, multiplied by the quantity containing the dose on hand, with both doses in the same unit.
Why must weight be in kilograms for pediatric doses?
Weight-based doses are written per kilogram; using pounds would give more than twice the intended dose.
Where can I find a free HCA 105 Module 5 sample paper?
This page contains the complete dosage calculation paper with its worked-problem table and commentary, open to all at no cost. It is the fifth HCA 105 sample.
How do I calculate a liquid dose in HCA 105 Module 5?
Divide the ordered dose by the dose in the available liquid and multiply by the volume that contains it, for example 500 mg divided by 250 mg, times 5 mL, equals 10 mL.