Every TEAS percent problem has a base: the whole, or the original amount before a change. Find the base first, then use part = percent × base. Percent change divides the change by the original amount. This free lab makes you mark the base before you calculate, then shows a bar model and each step.
The base is the amount that counts as 100%: the whole group, or the original amount before a change. Words like “of the”, “original”, “before” and “from” usually point to it.
Once you know the base, every percent problem is the same equation: part = percent × base. If the part is unknown, multiply. If the percent is unknown, divide the part by the base. If the base is unknown, divide the part by the percent.
Percent change = (new − original) ÷ original × 100. The original amount is the base. Going from 80 to 100 is a 20 ÷ 80 = 25% increase, but going from 100 back to 80 is a 20 ÷ 100 = 20% decrease, because the base changed.
For a new amount after a change, multiply by 1 plus or minus the rate: a 15% raise multiplies by 1.15, and a 15% discount multiplies by 0.85. Two changes multiply: +10% then −10% gives 1.10 × 0.90 = 0.99, a 1% net decrease, not zero.
Divide, do not add back. After a 20% discount the sale price is 80% of the original, so original = sale price ÷ 0.80. A $64 sale price came from $64 ÷ 0.80 = $80.
Adding 20% of $64 back gives $76.80, which is wrong because it uses the sale price as the base.
A rise from 15% to 20% is 5 percentage points, but it is a one-third (about 33.3%) increase relative to 15%. Read which one a question asks for.
The TEAS 7 Math section has 38 questions in 57 minutes, and 34 of them are scored. ATI groups the scored math questions into Numbers and Algebra (18) and Measurement and Data (16). Percent problems belong to Numbers and Algebra, and ATI’s help page lists percentages, including finding percentages of numbers and percentage increase or decrease, among the math to know.
Questions are usually short stories about prices, groups or amounts that changed. Many are multiple choice, where the wrong options are often the answers you get from the wrong base.
Percent change = (new − original) ÷ original × 100. A positive result is an increase and a negative result is a decrease. Always divide by the original amount, not the new one.
Divide the part by the whole (the base) and multiply by 100. 18 out of 24 is 18 ÷ 24 = 0.75, which is 75%.
Divide the part by the percent written as a decimal. If 36 is 45% of a number, the number is 36 ÷ 0.45 = 80.
The base changes. 80 up 25% is 100, but 100 down 25% is 75, because the second 25% is taken of 100, not of 80.
Yes. ATI says a basic on-screen calculator is built into the exam and is available on every question in every section. It adds, subtracts, multiplies and divides, and has percent, square root, decimal point, backspace and memory keys. It is not a scientific or graphing calculator, and personal, phone and watch calculators are not allowed.
Facts checked 2026-10-25. Practice items and data in this lab are original and invented; they are not real TEAS questions.
TEASPATH is independent of ATI. ATI TEAS® and TEAS® are registered trademarks of Assessment Technologies Institute, L.L.C., which is not affiliated with and does not endorse TEASPATH. Practice results are not official scores or admission predictions.
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