Quant Daily Daily timed GRE & GMAT drills

Quantitative comparison

GRE quantitative comparison — evaluate both quantities, then choose

GRE quantitative comparison gives you Quantity A and Quantity B and always the same four options: A is greater, B is greater, the two are equal, or the relationship cannot be determined. Evaluate or simplify both sides before comparing. The fourth option is correct only when the given information genuinely permits more than one ordering.

The options never change, which is the format's great advantage and its main trap. Because the answer choices carry no information, the work is entirely in simplifying the two quantities — and because 'cannot be determined' is always available, it attracts every candidate who has run out of time. A quantity that evaluates to a single number is never indeterminate.

Try it against the clock. Quantitative Comparison runs at 75s easy, 75s medium and 75s hard. The clock is stamped and judged on our server, so the limit you see is the deadline that is actually enforced — and it starts when you tap Start, not while the question is loading.

Start a timed Quantitative Comparison drill →

How to work a GRE quantitative comparison in under a minute

  1. Evaluate anything that reduces to a number

    If Quantity A is 3² and Quantity B is 6, then A is 9 and the comparison is finished. Two expressions that merely look different are not grounds for choosing the fourth option.

  2. Simplify both sides the same way before comparing

    Subtracting the same value from both quantities, or dividing both by the same positive number, preserves the comparison and often collapses it to something obvious.

  3. Reserve the fourth option for genuine variability

    Choose 'cannot be determined' only when you can construct two cases that order the quantities differently. If you cannot produce that second case, the answer is one of the first three.

  4. Test boundary values when variables are involved

    Try zero, one, a negative and a fraction. These four cover nearly every way a relationship can reverse, and if they all agree the relationship almost certainly holds.

What each of the four fixed options actually claims

OptionIt is correct when
Quantity A is greaterA exceeds B in every permitted case
Quantity B is greaterB exceeds A in every permitted case
The two are equalThey evaluate to the same value
Cannot be determinedTwo valid cases order them differently
Both evaluate to numbersThe fourth option is impossible

3 sample gre quantitative comparison, with worked solutions

Generated by the same engine that mints the Quant Daily daily. Each answer is computed from the numbers printed in the question, and the walkthrough below each one is the engine's own working — not a solution written afterwards. Reload this page's live drill and you get different numbers.

Question 1

Quantity A: x, where x is a positive integer

Quantity B: 8

Compare Quantity A and Quantity B.

  1. Quantity A is greater.
  2. Quantity B is greater.
  3. The two quantities are equal.
  4. The relationship cannot be determined from the information given.
Show the worked solution
  1. x can be less than, equal to, or greater than 8.
  2. No further restriction is given.
  3. QC strategy · When to pick D: Try two legal values of the unknown. If the comparison flips, the answer is D.
  4. Answer: The relationship cannot be determined from the information given.

Question 2

Quantity A: days two workers need together if they take 15 and 30 days alone

Quantity B: 15 (the faster worker alone)

Compare Quantity A and Quantity B.

  1. Quantity A is greater.
  2. Quantity B is greater.
  3. The two quantities are equal.
  4. The relationship cannot be determined from the information given.
Show the worked solution
  1. Combined rate 1/15 + 1/30 = 1/10.
  2. Together 10 days.
  3. Quantity A = 10. Quantity B = 15.
  4. QC strategy · Simplify: Evaluate both quantities before you compare. When Quantity B is greater, the answer is B — not D, and not C just because the expressions look different.
  5. Answer: Quantity B is greater.

Question 3

Quantity A: x, where x is a positive integer

Quantity B: 4

Compare Quantity A and Quantity B.

  1. Quantity A is greater.
  2. Quantity B is greater.
  3. The two quantities are equal.
  4. The relationship cannot be determined from the information given.
Show the worked solution
  1. x can be less than, equal to, or greater than 4.
  2. No further restriction is given.
  3. QC strategy · When to pick D: Try two legal values of the unknown. If the comparison flips, the answer is D.
  4. Answer: The relationship cannot be determined from the information given.

Common mistakes this drill is built from

The wrong options are not random numbers. Each one is the result of a specific careless error for this topic, so picking one tells you which habit is costing you marks.

Choosing the fourth option out of time pressure

It is always on the page and always tempting. When both quantities reduce to fixed numbers, it cannot be the answer no matter how different they look.

Selecting 'equal' because the forms differ

Two expressions written differently may still be unequal. Evaluate before deciding, rather than inferring from appearance.

Testing only positive integers

Relationships involving variables frequently reverse at zero, at fractions or across negatives. A single well-chosen value overturns a confident answer.

Why your answer came out wrong

The specific wrong numbers this topic produces, and what each one tells you about the step you took. If you have just got a question wrong and want to know which habit did it, start here.

Quantity A is the GCD of 24 and 40, Quantity B is 9. Is this indeterminate?

No. The GCD of 24 and 40 is exactly 8, and 8 is less than 9, so Quantity B is greater. Both sides are fixed numbers, which rules the fourth option out entirely — an expression you have not evaluated yet is not the same as an undetermined one.

If two quantities look completely different, should I pick 'equal' or 'cannot be determined'?

Neither, on appearance alone. Different-looking expressions are often equal and often not; the only way to know is to simplify both. Choosing on the basis of visual dissimilarity is guessing dressed up as reasoning.

I tried x = 2 and x = 5 and Quantity A won both times. Is A greater?

Not established. Both values you tried were positive integers greater than one, which is a narrow slice. Test zero, a fraction such as one half, and a negative — these are where comparisons reverse, and the question is usually built around exactly that reversal.

FAQ

What are the four answer choices in quantitative comparison?

Quantity A is greater, Quantity B is greater, the two quantities are equal, or the relationship cannot be determined from the information given. They are identical in every question of this type, so the entire task is deciding which of the four the two quantities support.

When is 'cannot be determined' actually correct?

Only when the information allows more than one ordering — that is, when you can build two cases that give different answers. If both quantities evaluate to specific numbers, the relationship is fixed and that option is eliminated regardless of how the expressions look.

Should I calculate both quantities fully?

Calculate when the arithmetic is short, and simplify when it is not. Removing a common term from both sides or dividing both by the same positive number preserves the comparison and often makes the answer visible without finishing either calculation.

Practise the next topic

Start a timed Quantitative Comparison drill →

Quant Daily is free, needs no account, and is not affiliated with ETS or GMAC. GRE Practice only — GMAT Practice does not include this kind.