   ## The Square Code

Here is another way to write secret codes. In this one, your message will be all
numbers. This will fool those who don't know your trick. This is called the
square code because the alphabet is arranged in a square, five rows and five
columns. Your coding device will look like this:

1 2 3 4 5
1 A B C D E
2 F G H I J
3 K L M N O
4 P Q R S T
5 U V W X Y

To use this as a coding device you must follow the row, column rule. Always
give the letter's row first then its column. Remember, rows go left to right,
and columns go top to bottom. The numbers on the left of the square array are
row numbers, and the numbers on the top are column numbers. In the square above,
K is in the third row, first column, so K would be 31. T on the other hand is in
the fourth row, and fifth column so it would have a value of 45. Remember, we
always say row first then column.

So, how does "Meet me after school" look when coded with the square?
M is 33, E is 15 and T is 45, so the first word is 33,15,15,45.

Try the next few words by your self to get some practice.

The five by five square code is fine but it does have a problem. Did you notice
there was no pair for the letter Z? That is easily fixed if you and your friend
agree that 00 represents the letter Z. However, there is another problem with the five
by five that we don't recognize until we try to put numbers in our message.
Writing them out takes a lot of time. There is a better solution, the six by six
square. It works just like the five by five, but in addition to letters, it also
contains numbers. A six by six follows. It is your choice which one you use.
Happy coding!

1 2 3 4 5 6
1 A B C D E F
2 G H I J K L
3 M N O P Q R
4 S T U V W X
5 Y Z 1 2 3 4
6 5 6 7 8 9 0