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Curated by: Khan Academy India - English (21 videos)
If all the letters of the word MATH are rearranged and put in a dictionary, what will be the rank of the word MATH? We tackle this problem and a few similar ones in this video. We realise that there are two ways to solve these problems. Slower method involves listing down all possible arrangements and then manually hunting down the word we're looking for. This is tedious and prone to errors. A much faster method is to calculate the number of words starting with first letters. This helps us navigate the dictionary neatly. Courses on Khan Academy are always 100% free. Start practicing—and saving your progress—now! (https://www.khanacademy.org/math/ncert-class-11/xea4762213f311c5e:permutations-and-combinations-ncert-new/xea4762213f311c5e:untitled-900/e/permutations_1) Timestamps: 00:00 Problem 1 (Finding the rank of MATH) 01:35 Slower solution (listing down all possible arrangements) 02:56 Faster solution (calculating number of words for first letters) 04:00 Problem 2 (Finding 50th word AGAIN's rearrangements) 06:38 Problem 3 (Finding words before the first word starting with E) Khan Academy India is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We have videos and exercises that have been translated into multiple Indian languages, and 15 million people around the globe learn on Khan Academy every month. Support Us: https://india.khanacademy.org/donate Created by Ashish Gupta