Quantitative Reasoning: The Four Question Formats
The four shapes a GRE quant question can take, plus the on-screen calculator - starting with quantitative comparison, where most points are quietly lost.
12 topics · 50 questions
Each topic is a path, not a menu: work down it in order and every question builds on the one above. Click any of them to watch the answer draw itself.
Quantitative Comparison: The Four Fixed Answer Choices
- How it worksHow do the four choices map onto Quantity A greater, Quantity B greater, the two equal, and cannot be determined?
- How it worksWalk me through reading a comparison item so you never flip Quantity A greater and Quantity B greater by accident.
- Worked exampleFind which is greater when Quantity A is 3 to the 4th power and Quantity B is 4 to the 3rd power.
- Common mistakeWhy isn't there ever a fifth choice, like both quantities are negative, on a GRE comparison item?
- Going furtherWhat happens to the four choices when both quantities turn out to be the same number written two ways?
Quantitative Comparison: Cannot Be Determined
- How it worksHow does finding two cases that point opposite ways prove a relationship cannot be determined?
- Worked exampleFind the relationship between Quantity A equal to x squared and Quantity B equal to x cubed with no restriction on x.
- Common mistakeWhy isn't cannot be determined the right choice just because a comparison item contains a variable?
- Common mistakeWhy doesn't a messy-looking comparison mean the relationship is genuinely undetermined?
- Going furtherWhat happens to cannot be determined once an item pins the variable to one single value?
Quantitative Comparison: Compare, Don't Compute
- How it worksHow do you strip matching pieces off both quantities until only the real difference is left?
- Worked exampleCompare 17 times 23 against 16 times 24 without multiplying either pair out.
- Common mistakeWhy doesn't computing both quantities in full count as the safe way to answer a comparison item?
- Worked exampleFind which is greater, 7 over 9 or 8 over 11, without converting either fraction to a decimal.
Quantitative Comparison: Simplifying Both Sides in Parallel
- How it worksHow do you add, subtract or divide the same thing on both sides of a comparison without breaking it?
- How it worksWalk me through why multiplying both quantities by a negative number reverses which one is bigger.
- Worked exampleCompare Quantity A equal to 3x plus 7 with Quantity B equal to 7 plus 2x when x is greater than 0.
- Common mistakeWhy isn't cross multiplying two fractions in a comparison safe when a denominator could be negative?
Quantitative Comparison: Testing Strategic Values
- How it worksHow does one value that makes A bigger and another that makes B bigger settle an item instantly?
- Worked exampleFind the relationship between Quantity A equal to x and Quantity B equal to x squared by testing 0, one half and 2.
- Worked exampleCompare Quantity A equal to 1 over n with Quantity B equal to n when n is any nonzero number.
- Common mistakeWhy doesn't testing three numbers that all agree prove the relationship holds for every number?
- Going furtherWhat extra test values do you need once an item says the variable has to be an integer?
Quantitative Comparison: Restricted Domains and Given Conditions
- How it worksHow does a stated restriction shrink the set of test numbers you are allowed to try?
- Going furtherWhat happens to a comparison when the restriction rules out every value that made the sides disagree?
- Worked exampleCompare Quantity A equal to x squared with Quantity B equal to x when x is between 0 and 1.
- Common mistakeWhy isn't a condition like y is not zero the same as a condition saying y must be positive?
Quantitative Comparison: The Errors That Cost Points
- How it worksHow do you spend under two minutes on a comparison item and know the moment to guess and move on?
- Common mistakeWhy isn't the bigger-looking expression automatically the greater quantity on a comparison item?
- Worked exampleFind the relationship when Quantity A is the average of 10 and 20 and Quantity B is the average of 12 and 18.
- Going furtherWhat changes in your approach when a comparison item shows a figure that is not drawn to scale?
Multiple-choice: Select One Answer Choice
- How it worksHow do the answer choices themselves tell you whether to estimate or to compute exactly?
- Worked exampleFind the approximate cost of gasoline for a 350 mile drive at 33 miles per gallon and 2.95 per gallon.
- Common mistakeWhy isn't the number sitting at the end of your scratch work always the number the question asked for?
- Going furtherWhat happens when you work backwards from the middle answer choice instead of solving forwards?
Multiple-choice: Select One or More Answer Choices
- How it worksHow do you judge each choice on its own merits instead of comparing the choices against each other?
- Common mistakeWhy isn't the number of correct choices always stated somewhere in the question stem?
- Worked exampleFind every value among 8, 12, 15, 18, 21 and 36 that is a multiple of both 2 and 3.
- Going furtherWhat changes when a select-all question asks for values in a range rather than items on a list?
- Ties togetherHow does pinning down the least and greatest possible average turn a select-all item into a range check?
Numeric Entry: The Single Answer Box
- How it worksHow do you check units, rounding and order of magnitude before typing a numeric entry answer?
- Common mistakeWhy isn't 46.7 an acceptable entry when a question asks for the answer rounded to the nearest integer?
- Worked exampleFind the total cost of 18 pens at 25 cents each and 100 markers at 35 cents each.
Numeric Entry: Fractions in Two Boxes
- How it worksHow do you enter a fraction answer when the numerator and the denominator get their own boxes?
- Going furtherWhat happens if you type 20 over 80 when the fully reduced answer would be 1 over 4?
- Common mistakeWhy doesn't the calculator's Transfer Display button work on a two-box fraction answer?
The On-Screen Calculator and When to Skip It
- How it worksHow does the on-screen calculator follow order of operations differently from a cheap pocket calculator?
- Worked exampleWalk me through computing the square root of 21 squared plus 54 squared without the root swallowing one term.
- Going furtherWhat happens on the GRE calculator when a result runs past eight digits or you divide by zero?
- Ties togetherHow does estimating first protect you from a mis-keyed calculator answer on a percent problem?
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