Maths Puzzles

 The puzzle was A teacher wrote down a number on the board asked the students to check the divisors of the number one by one.       The first student said that the number is divisible by 2.       The second student said that the number is divisible by 3.       And so on.         The 30th student said that the number is divisible by 30.        The last student said that the number is divisible by 31. Now the teacher said that exactly two students who told about consecutive divisors are wrong. Which are those two numbers?  Solution : Let us consider that the numbers is not divisible by are 2 and 3. If so, then the number will not be divisible by all even numbers and all products of 3. So 2 and 3 are not our answer.  Using similar argument, we can remove numbers from 7 and 8. Because if number is not divisible by 8, it won’t be divisible by 16.  So we can omit the numbers 2 to 10, 11 and 12 (as it is divisible by 3 and 4, it is divisible by 12), 13 14 15. But if we take the numbers as 16

 A teacher wrote down a number on the board asked the students to check the divisors of the number one by one.       The first student said that the number is divisible by 2.       The second student said that the number is divisible by 3.       And so on.         The 30th student said that the number is divisible by 30.        The last student said that the number is divisible by 31. Now the teacher said that exactly two students who told about consecutive divisors are wrong. Which are those two numbers?  The solution can be found here .   

 This one is not exactly a puzzle. But it's my favorite subject though.  I had once written an android game called Shataka, then renamed to Hundred . The aim of the game was to add numbers to 100.  This puzzle is similar. You are given a grid of 3X3 with 9 numbers. Make each row and column add up to 100 by adding digits to the numbers in the cells. I have borrowed the puzzle from mathinenglish .com website. 9 5 8 1 2 2 7 2 3 For example, if you add one digit each to first row, you can write 91, 15 and 8. But that will not be correct as it does not add up to 100.  So let us try to find a solution.