Counting problems on the GRE are a test of logic, not just formulas. Whether it's a Numeric Entry question or a Quantitative Comparison, success comes from knowing when to multiply, when to add, and when to subtract.
The most critical step is the first one. Learn to distinguish between a 'Selection' (Combination) and an 'Arrangement' (Permutation) using our visual Team vs. Photo scenarios.
Stop using nPr and nCr formulas blindly. Learn the intuitive 'Countdown Method' (Slot Method) to calculate arrangements and selections faster and with fewer errors.
Learn how to handle scenarios where specific items MUST be chosen or MUST be excluded from the group.
How do you seat people if two friends refuse to be separated? Learn the 'Glue' technique to treat multiple items as a single unit.
Calculating 'Never Together' directly is messy. Learn the powerful shortcut of subtracting the 'Together' cases from the Total to find the answer instantly.
What happens when the items aren't unique (like the letters in MISSISSIPPI)? Learn how to adjust your calculation to account for duplicates.
Numeric Entry questions often ask for 'at least one' scenarios. Calculating these directly is slow. Learn the 'Total minus None' shortcut to solve them in seconds.
How to use 'Extreme Values' to find the range of a sum without calculating every fraction.
Stop calculating! Learn how to use the properties of symmetry to solve hard SD questions in seconds.
Forget formulas for a moment. Learn the 'Systematic Listing' method to build an unshakable intuition for Permutations & Combinations.