Retired Pittsburgh math teacher Walter W. Horner devised this doubly magic square in 1955:

Each row, column, and long diagonal produces both a sum of 840 and a product of 2058068231856000.

And Rodolfo Marcelo Kurchan of Buenos Aires discovered this remarkable square in 1991:

Each number contains all 10 digits — and so does the magic sum, 4129607358.