Howard W. Bergerson devised these:
As in a word square, the “columns” in each sum are identical with the “rows.”
12/07/2021 UPDATE: Reader James Foster finds that 20 such squares are possible. (Thanks, James.)
Howard W. Bergerson devised these:
As in a word square, the “columns” in each sum are identical with the “rows.”
12/07/2021 UPDATE: Reader James Foster finds that 20 such squares are possible. (Thanks, James.)