Let

*a* be the top left value,

*b* the top middle, and so on to

*i* at the bottom right.

*f* is even and prime so must be 2. By clue 3, *d* and *e* are 3 and 5 in some order. *e* can not be 5 as then clue 1 could not be met. Therefore, *d* = 5 and *e* = 3. The left column must consist of {5, 7, 9} and the right {2, 4, 6}.

To meet clue 4, *i* = 6 (so *c* = 4), *g* = 7 (so *a* = 9), and *h* = 8 (so *b* = 1).

The solution is *a* = 9, *b* = 1, *c* = 4, *d* = 5, *e* = 3, *f* = 2, *g* = 7, *h* = 8, and *i* = 6.