GRE Quant · Study & Practice

Percentages

AreaArithmetic DifficultyEasy–Medium GRE weightageHigh — appears directly and inside ratios, interest, mixtures, and Data Interpretation sets

Percentages are the most reused idea in the entire GRE Quant section. A "percent" simply means "per hundred", so every percentage is just a fraction with a denominator of 100 — and once you see it that way, interest, growth, data interpretation, mixtures and even Quantitative Comparison questions all become the same skill in different clothes. The GRE rarely asks a bare "find 20% of 80"; instead it buries percentages inside word problems and Data Interpretation, and rewards test-takers who can convert between fractions, decimals and percents instantly, handle successive changes without slipping, and work backwards from a final value. Because the on-screen calculator is basic and slow, the students who score highest do most of this in their heads. This chapter builds that fluency from the ground up — the conversions, the change formulas, the successive-change shortcut, reverse percentages, and the high-frequency GRE applications — each with worked examples, the fastest method, and the traps that quietly cost points.

Topics

1 Percent Basics & Conversions 4 worked · 5 practice · 8-Q test Start → 2 Percentage Change 4 worked · 5 practice · 8-Q test Start → 3 Successive Percentage Change 4 worked · 5 practice · 8-Q test Start → 4 Reverse Percentages 4 worked · 5 practice · 8-Q test Start → 5 Percent Applications 4 worked · 5 practice · 8-Q test Start →

⚡ GRE shortcuts & speed methods

The fastest ways to crack this chapter under time pressure — the techniques that separate a 95+ percentiler from the rest.

  • Learn the fraction–percent table by heart. Reading 62.5% as 5/8 turns a calculator step into mental math.
  • Every percent change is a multiplier: +18% ⇒ ×1.18, −18% ⇒ ×0.82. Chain multipliers for successive changes.
  • Successive a% then b% = a + b + ab/100. The ab/100 cross term is exactly what people forget.
  • Reverse percentages DIVIDE: after +x%, original = final / (1 + x/100). Never multiply back.
  • x% of y = y% of x. So 18% of 50 = 50% of 18 = 9 — flip it to make the arithmetic trivial.

⚠️ Common mistakes & traps

GRE is designed so that careless errors here cost you marks. Internalise each trap before the exam.

  • Using the NEW value as the base for percent change instead of the original.
  • Adding successive percentages (20% + 30% = 50%) instead of compounding them (= 56%).
  • Reversing a change by multiplying (final × 0.8 after a 20% rise) instead of dividing by 1.2.
  • Confusing a percentage-POINT change with a percent change (5% → 7% is +2 points but +40% relative).
  • In Data Interpretation, taking a percent of the wrong whole (a category total vs the grand total).

📈 GRE exam insight & question patterns

Quantitative Comparison — Column A: the result of increasing 100 by 20% then decreasing by 20%. Column B: 100. Which is greater?

Column B. 100 × 1.2 × 0.8 = 96 < 100. (The GRE loves this "they don’t cancel" trap.)

Data Interpretation — a table shows sales rose from 250 to 300 units. What was the percent increase?

(50/250) × 100 = 20%. Anchor to the original 250.

Numeric Entry — a $90 item is on sale for $72. Enter the discount percent.

(18/90) × 100 = 20%.

🎴 Flashcards — instant recall

Tap a card to reveal the answer. Drill these until they are automatic.

x% of NTap to reveal
(x/100) × N
Percent changeTap to reveal
(new − old) / old × 100 %
Successive a% then b%Tap to reveal
a + b + ab/100 (%)
Reverse a +x% changeTap to reveal
original = final / (1 + x/100)
A is x% more than B ⇒ B isTap to reveal
[x/(100 + x)] × 100 % less than A
1/8 as a percentTap to reveal
12.5%

📌 Quick revision

Percent means "out of 100", so treat every percent as a fraction or a decimal multiplier and the whole topic collapses into arithmetic you can do in your head. Convert fluently, compute change against the ORIGINAL base, compound successive changes with a + b + ab/100 (or a multiplier chain), and DIVIDE to reverse a change. Then recognise the costumes — profit/discount, interest, growth, mixtures and Data Interpretation are all the same skill. Master this chapter and you have quietly prepared for a large slice of the GRE Quant section, including many Quantitative Comparison and Data Interpretation questions.

Chapter test

📝 Percentages — Chapter Test
25 fresh questions · timed · full solutions
Start chapter test →
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🏆 Vidaara GRE success checklist

You have truly mastered Percentages when you can tick every box below.

  • Recall every formula in this chapter without looking them up
  • Solve each topic’s practice set with at least 80% accuracy
  • Use the chapter shortcuts to cut your solving time in half
  • Spot and avoid every common trap listed above
  • Score 80%+ on the timed chapter test

📋 Chapter mastery scorecard

Track where you stand. Aim for the target before moving to the next chapter.

Skill checkpointTarget
Concept theory & formulas understood100%
Topic practice sets attempted (5 topics)5/5
Best topic-test score— → 80%+
Chapter test score— → 80%+
Flashcards drilled to instant recall6 cards