Letter Block

Eight wooden blocks are lettered, and are placed in a box, as shown in the illustration. 

You can only move one block at a time to the place vacant for the time being, as no block may be lifted out of the box. 
The puzzle is to shift them about until you get them in the order—

A  B  C
D  E  F
G  H

Do it in the fewest possible moves. 

See answer

Math Genius