This is an optional module for those appearing only for the Engineering exams. Practice Problems Q-1) Find the number of 2 digit positive integers that are divisible by both of their digits. Q-2) How many ways are there to arrange the numbers 1,2,3…,64 on a 8×8 chessboard such that the numbers in each row and… Continue reading
Tag: ISI
Week -13 | Combinatorics – 9
In this module, we’d discuss a couple of counting strategies that maybe useful while solving problems related to the Olympiads. We’d illustrate these strategies with the help of examples. Ex-1) Let be integers greater than 1. Consider to be a set with elements, and let be subsets of . Assume that for any 2 elements , there… Continue reading
Week -13 | Combinatorics – 8
Practice Problems Q-1) There are p intermediate stations on a railway line between 2 points A and B. In how many ways can a train stop at 3 of the stations such that no 2 of the stopping stations are consecutive? Q-2) How many different numbers smaller than can be formed by the digits 0,1,2… Continue reading
Week – 12 | Combinatorics – 7
This is an optional module for students preparing for the engineering entrance exams. Q-1) Among 6 persons in a room, there are either 3 who know each other or 3 who are complete strangers Solution : Let us consider a hexagon with each person denoting a specific vertex of the hexagon. We join 2 vertices… Continue reading
INMO 1988 | A problem on Equations
Q) Show that there cannot be distinct positive integers such that and . Solution: This problem trivially arrives to a scenario that we have covered in the module ‘System of Equations’. And it touches a very important concept that is useful in many scenarios. We have . Cubing both sides, and cancelling out the common terms (assuming… Continue reading