Subcontests
(5)no 2, 3, 4, 5 in squares of 5x5 board , 2018 May Olympiad L1 p5
In each square of a 5×5 board one of the numbers 2,3,4 or 5 is written so that the the sum of all the numbers in each row, in each column and on each diagonal is always even. How many ways can we fill the board?Clarification. A 5×5 board has exactly 18 diagonals of different sizes. In particular, the corners are size 1 diagonals. a list of 2018 numbers , max last no 2018 May Olympiad L1 p1
Juan makes a list of 2018 numbers. The first is 1. Then each number is obtained by adding to the previous number, one of the numbers 1, 2, 3, 4, 5, 6, 7, 8 or 9. Knowing that none of the numbers in the list ends in 0, what is the largest value you can have the last number on the list?