MathDB
numbers in a 2015 x 2015 table

Source: 2016 Saudi Arabia Pre-TST Level 4+ 1.4

September 13, 2020
combinatoricstable

Problem Statement

The natural numbers 0,1,2,3,...0, 1, 2, 3, . . . are written on the square table 2015\times 2015 in a circular order (anti-clockwise) such that 00 is in the center of the table. The rows and columns are labelled from bottom to top and from left to right respectively. (see figure below) 1. The number 20152015 is in which row and which column? 2. We are allowed to perform the following operations: First, we replace the number 00 in the center by 1414, after that, each time, we can add 11 to each of 1212 numbers on 1212 consecutive unit squares in a row, or 1212 consecutive unit squares in a column, or 1212 unit squares in a rectangle 3×43\times 4. After a finite number of steps, can we make all numbers on the table are multiples of 20162016? https://cdn.artofproblemsolving.com/attachments/c/d/223b32c0e3f58f62d0d40fa78c09a2cd035ed5.png