Permutations & Combinations (P&C) is a high-weightage topic in CAT Quant. It also forms the logical foundation for Probability. This guide moves beyond basic formulas to cover the advanced constraints and circular arrangements tested on the CAT.
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.
Real CAT problems have rules. 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.
Arranging people in a circle is different from a straight line because there is no 'start' or 'end'. Learn the (n-1)! rule and why it works.
Forget formulas for a moment. Learn the 'Systematic Listing' method to build an unshakable intuition for Permutations & Combinations.
Stop calculating! Learn how to use the properties of symmetry to solve hard SD questions in seconds.
How to use 'Extreme Values' to find the range of a sum without calculating every fraction.
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