The puzzles all involved the cube. The solutions are below.
A. Arrange the numbers 1-8 on the corners of a cube so that the 6 faces have magic sum 18.
B. Arrange the numbers 0-7 on the corners of a cube so that the connecting edge always has a prime sum.
C. Arrange the numbers 1-12 on the edges of a cube so that faces and parallel edges have magic sum 26.
D. Arrange the numbers 1-12 on the edges and (0,1,2,3,4,7,9,12) on the corners of a cube so that each edge gives the difference between the corners it connects.