Math Review/ Learn
Jean Montgomery, Austin Community College

Rounding Rules

Medications are administered in several different forms including liquid, powder, tablets, capsules, injections, and infusions. The most common forms of drug that you will prepare and administer are liquid and tablets. When you calculate the dose of medication to be administered, there will be occasions when your answer will not be a whole number. You must decide how much medication to administer based on your answer and the form of drug to be administered.

More often that not, when you prepare and administer a liquid or injectable medication, you will need to round to the nearest tenths place.

 Place Value Table 5 4 3 2 1 . 1 2 3 4 Ten Thousands Thousands Hundreds Tens Ones Decimal Point Tenths Hundredths Thousandths Ten Thousandths

However, when preparing medications for infants and children or when administering specific drugs, you have to round to the nearest hundredths place.

Rules
1. Rounding to nearest whole number
1. If the amount to be administered is greater than 0.5, then round up to the whole number.
Example:
You have calculated a dose to be 4.7 tablets. Because 0.7 is greater than 0.5, you would round up to the whole
Therefore, the dose would be 5 tablets.
2. If the amount to be administered is less than 0.5, round down to the whole number.
Example:
You have calculated a dose to be 2.4 tablets. Because 0.4 is less than 0.5, you would round down to the whole number.
Therefore, the dose would be 2 tablets.
2. Rounding to the nearest tenths place
1. If the amount to be administered is greater than 0.5, then round up to the tenths place.
Example:
You have calculated a dose to be 4.56 mL's. Because 0.56 is greater than 0.5, you would round up to the tenths place.
Therefore, the dose would be 4.6 mL's.
2. If the amount to be administered is less than 0.5, then round down to the tenths place.
Example:
You have calculated a dose to be 4.34 mL's. Because 0.34 is less than 0.5, you would round down to the tenths place.
Therefore, the dose would be 4.3 mL's.

When your answer is not a whole number, you must determine if the dosage form can be safely divided. Certain types of medication cannot or should not be divided:

1. unscored tablets
2. extended release medications - designated with XL, XR, or ER
3. enteric coated tablets - designated with EC
4. capsules

These types of medications cannot be broken or divided safely and would cause the drug to be improperly absorbed and utilized by the body. Some tablets are scored with one or two dividing lines. These tablets can safely be broken in half or in fourths to provide the correct dose.