Here's why:

* Magnetic field lines: Magnetic fields are represented by lines of force that flow from the north pole to the south pole of a magnet. The lines are closest together at the poles, indicating a higher concentration of magnetic force.

* Magnetic flux density: Magnetic flux density (measured in Tesla) is a measure of the strength of the magnetic field. It's highest at the poles, where the lines of force are most concentrated.

* Force on a magnetic dipole: A magnet can be thought of as a magnetic dipole, with a north and south pole. When a magnet is placed in an external magnetic field, the strongest force is experienced at the poles where the dipole interacts most strongly with the external field.

Therefore, the strongest magnetic force on a magnet is experienced at its poles, where the magnetic field is most concentrated.