Study guide
3.3 Decimals and Percentages
ATI TEAS 7 Nursing Admission
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1 Introduction to the ATI TEAS 7
1.1 About the ATI TEAS 7 Exam 1.2 Content Area Breakdown 1.3 Scoring and Program Requirements 1.4 Building Your TEAS Study Plan
2 Reading
2.1 Identifying the Main Idea 2.2 Making Inferences and Drawing Conclusions 2.3 Summarizing and Paraphrasing 2.4 Understanding Text Structure 2.5 Author's Purpose, Tone, and Point of View 2.6 Evaluating Arguments, Evidence, and Credibility 2.7 Integrating Information and Interpreting Graphics 2.8 TEAS Reading Strategies, Pacing, and Practice
3 Mathematics
3.1 Whole Numbers and Basic Operations 3.2 Fractions 3.3 Decimals and Percentages 3.4 Ratios and Proportions 3.5 Algebra and Equations 3.6 Measurement and Unit Conversions 3.7 Statistics and Data Interpretation 3.8 Geometry Basics
4 Science
4.1 The Cardiovascular System 4.2 The Respiratory System 4.3 The Digestive System 4.4 The Nervous System 4.5 The Musculoskeletal System 4.6 The Urinary and Reproductive Systems 4.7 Cell Biology and Genetics 4.8 Chemistry Basics 4.9 Scientific Reasoning and the Scientific Method
5 English & Language Usage
5.1 Grammar and the Parts of Speech 5.2 Sentence Structure 5.3 Punctuation 5.4 Spelling and Word Usage 5.5 Vocabulary in Context and Word Parts 5.6 Paragraph Organization and the Writing Process 5.7 Formal vs. Informal Language, Audience, and Tone 5.8 TEAS English Section Strategies and Pacing
3.3 Decimals and Percentages
Key Takeaways Explain This Topic AI
Convert a decimal to a percent by multiplying by 100 (move the point two places right); reverse it by dividing by 100
Memorize core equivalents such as 1/4 = 0.25 = 25% and 1/2 = 0.5 = 50% to save time
Find a percent of a number by converting the percent to a decimal and multiplying
Percent change = (new − original) ÷ original × 100, where a negative result is a decrease
- When multiplying decimals, the answer has as many decimal places as the two factors combined
- Last updated: October 2026
Decimals and Percentages on the TEAS
Healthcare runs on decimals and percentages: a glucose reading of 95.5 mg/dL, a 0.9% saline solution, a 0.25 mg tablet. The ATI TEAS 7 reflects this by testing decimal operations and the ability to move fluidly among fractions , decimals , and percentages . Because a misplaced decimal in nursing can be a tenfold dosing error, the exam rewards careful place-value alignment over speed.
Decimal Place Value
- Place Value Digit in 0.375
- Tenths 0.1 3 (represents 0.3)
- Hundredths 0.01 7 (represents 0.07)
- Thousandths 0.001 5 (represents 0.005)
Reading place value also drives rounding : to round 3.7846 to the nearest hundredth, look at the thousandths digit (4, less than 5) and round down to 3.78 .
Decimal Operations
Adding/Subtracting: line up the decimal points (add placeholder zeros so the columns match), then add or subtract as with whole numbers and bring the point straight down.
Worked Example: 3.45 + 2.6 → align as 3.45 + 2.60 = 6.05 .
Multiplying: ignore the points and multiply, then count the total number of decimal places in both factors and place that many in the product.
Worked Example: 1.5 × 2.4. Compute 15 × 24 = 360. The factors have 1 + 1 = 2 decimal places, so the product is 3.60 = 3.6 .
Dividing: move the divisor's decimal point to make it a whole number, move the dividend's point the same number of places, then divide.
Worked Example: 4.5 ÷ 0.5 → shift one place each to 45 ÷ 5 = 9 .
Converting Among Fractions, Decimals, and Percentages
- From → To Method Example
- Fraction → Decimal Divide top by bottom ¾ = 3 ÷ 4 = 0.75
- Decimal → Fraction Read place value, simplify 0.75 = 75/100 = 3/4
- Decimal → Percent Multiply by 100 0.75 → 75%
- Percent → Decimal Divide by 100 75% → 0.75
- Fraction → Percent Decimal, then ×100 ¾ = 0.75 = 75%
- Percent → Fraction Over 100, simplify 75% = 75/100 = 3/4
- Key Equivalents to Memorize
- Fraction Decimal Percent
- 1/4 0.25 25%
- 1/3 0.333… 33.3%
- 1/2 0.5 50%
- 2/3 0.666… 66.7%
- 3/4 0.75 75%
- 1/5 0.2 20%
- 1/10 0.1 10%
Knowing these by sight lets you skip conversion steps — if a question asks for 75% of a quantity, you can immediately think "three-quarters."
Percentage Calculations
Percent OF a number: convert the percent to a decimal and multiply.
Worked Example: What is 15% of 80? 0.15 × 80 = 12 .
What percent one number is of another: divide the part by the whole, then multiply by 100.
Worked Example: 15 is what percent of 60? 15 ÷ 60 = 0.25 → 25% .
Find the whole from a part and a percent: divide the part by the decimal form of the percent.
Worked Example: 12 is 20% of what number? 12 ÷ 0.20 = 60 .
Percent Change (Increase and Decrease)
Percent change = (new − original) ÷ original × 100. A positive result is an increase; a negative result is a decrease.
Worked Example (decrease): A patient's weight drops from 200 lb to 180 lb. Change = 180 − 200 = −20; −20 ÷ 200 × 100 = −10% , i.e., a 10% decrease.
Worked Example (increase): A heart rate rises from 60 to 75 bpm. Change = 75 − 60 = 15; 15 ÷ 60 × 100 = 25% increase . Note that you always divide by the original value, not the new one.
Dosage-Relevant Decimal Reasoning
Decimals are the backbone of dosage math. A common safety rule is to write a leading zero (0.5 mg, never .5 mg) and to avoid trailing zeros (5 mg, not 5.0 mg) so a misread point cannot create a tenfold error.
Worked Example (concentration): A 0.9% sodium chloride solution means 0.9 g of NaCl per 100 mL. How many grams are in 250 mL? Set up 0.9 g / 100 mL = x / 250 mL, or simply 0.009 × 250 = 2.25 g . Percent-as-decimal reasoning turns a wordy clinical statement into one multiplication.
Healthcare Applications
- Application Example
- Medication concentration 0.5 mg/mL
- Lab values Blood glucose 95.5 mg/dL
- IV rates 125.5 mL/hour
- Solution strength 25% dextrose
- Body composition 18.5% body fat