Problem:
Find all positive integer solutions to the following equation:
Solution
Solution:
A square must end in the digit , or . If , then ends in the digit , so cannot be a square. A simple check for the remaining cases reveals that the only solutions are and .
Want a route through all this instead of an archive? The track
puts 2,000 problems in a working order, from AMC 10 level to the IMO shortlist.