Decode the word coded inside the square:
A.O.O.E D 2
T D C.I.E D
C.A O E O C
E 2.E.2 O E
C O.D A D.E
The hint itself is hidden in the square.
There are two steps! The first shows what to use to decode the second step.
Rearranging the letters doesn't change anything.
Hint 4 (new):
First-grader would have more then enough math-skills to deal with the letters.