Percentages

What Bluebook is testing

Q.B. is percent of, percent change, and chained percents. Sometimes the unknown is the original, not the new amount.

How it shows up

Worded prices, populations, error rates. Hard items give the result after two changes and ask for the start, or compare two different bases.

A method that survives Module 2

Translate to multipliers: +20% is ×1.2, −20% is ×0.8. Multiply them. Name the base every time you see the word 'of.' If the original is unknown, call it x and apply the multipliers. Do not work backwards from a guess unless you check.

Traps that look like knowledge

• Adding percents that apply in sequence (20% + 10% ≠ 30% chained)
• Taking a percent of the new amount when they meant the original
• Percent increase vs percentage points
• Solving 'n is 25% of what' as 0.25n instead of n / 0.25

Questions

What is "Percentages" on the Digital SAT?

It is an official College Board skill in Digital SAT Math. The wording on Bluebook matches the domain taxonomy Drilled uses in drills, analytics, and the notebook.

How does Drilled train Percentages?

Filter the bank to the skill, run a timed drill, autopsy every miss, and let the notebook bring the same pattern back. Domain drills and full section sims include the skill at the official mix.

What is the most common trap on Percentages?

Adding percents that apply in sequence (20% + 10% ≠ 30% chained)

Related

• Problem-Solving and Data Analysis
• Ratios, rates, proportional relationships, and units
• One-variable data: Distributions and measures of center and spread
• Two-variable data: Models and scatterplots
• Probability and conditional probability
• Inference from sample statistics and margin of error
• Evaluating statistical claims: Observational studies and experiments