The triangle OMN has vertices on the axes with whole number co-ordinates. How many points with whole number coordinates are there on the hypotenuse MN?
Three people chose this as a favourite problem. It is the sort of
problem that needs thinking time - but once the connection is made
it gives access to many similar ideas.
Times and Square
Age 14 to 16 Short Challenge Level
Roger picks two consecutive integers, one of which ends in a 5.
He multiplies the integers together and then squares the result.