Extremal Principle is used in a variety of problems in Math Olympiad. The following problem from AMC 10 is a very nice example of this idea. AMC 10 Problem 4 (2019) A box contains 28 red balls, 20 green balls, 19 yellow balls, 13 blue balls, 11 white balls, and 9...

Geometric Transformation is a powerful tool in Geometry. We look at one such transformation: Spiral Similarity. Watch video Try these problems. Send answers to helpdesk@cheenta.com Problem 1: Suppose O = (0, 0), A = (2, 0) and B = (0, 2). Let T be the spiral...

Auxiliary polynomials are useful for solving complicated polynomial problems. This problem from ISI Entrance (and a Soviet Olympiad) is a good example. Watch video Read...

What are we learning ? Competency in Focus: Biquadratic Equations Main idea: It is usually hard to solve biquadratic equations. However, sometimes, combining tools from geometry and strategies like completing the square it is possible to do so. Look at the knowledge...

Understand the problem Alice has 24 apples. In how many ways can she share them with Becky and Chris so that each of the three people has at least two apples? Source of the problem American Mathematical Contest 2019, AMC 8 Problem 25 Topic Combinatorics Difficulty...