CLE TSE NTL OAL GID UW ANN ROO
Can you decode this message using the boxes method knowing that the key word is COMPUTER?
See development and solution
Development:
We create a table with $$8$$ columns (as many letters as the key has) and $$5$$ rows (the longest group of letters is $$3$$ letters, adding a line for the key and another one below for the numbers that indicate the order)
| C | O | M | P | U | T | E | R |
| $$1$$ | $$4$$ | $$3$$ | $$5$$ | $$8$$ | $$7$$ | $$2$$ | $$6$$ |
| C | O | N | G | R | A | T | U |
| L | A | T | I | O | N | S | W |
| E | L | L | D | O | N | E |
Solution:
The message says "congratulations well done".