A good answer might be:

i × i   =   0
j × j   =   0
k × k   =   0

Computing Cross Product from Column Matrices

Say that the vector u is represented by     u   =   (ui , uj , uk )T
and that the vector v is represented by     v   =   (vi , vj , vk )T.

Then   u × v   =   ( uj vk - uk vj ,   uk vi - ui vk ,   ui vj - uj vi )T.

There is a pattern in how this is formed. Look at it a bit. But don't even think of memorizing it.

QUESTION 11:

What is: (1, 2, 3)T × (0, 0, 0)T ?