by Khin La Pye Wone, University Of Maryland, Baltimore County

This WebQuest is about how to use inverse matrices in real life. Cryptogram will be introduce and students will learn how to convert, encode and decode a message.

# Let's break the code

### Cryptography is a method of preparing coded messages that can only be comprehend by using the "key" to the message.

#### The followings are the techniques of how to use a cryptogram.

• First, you have to assign a number to each letter of the alphabet.
• To encode the message, pair up all the numbers from the message, choose a matrix and multiply them. The message is now unreadable to anyone who does not have the key to the code.
• To decode the message, the recipient of the coded message have to multiply by the opposite, or inverse, of the coding matrix.

## Use the following table to encode or decode your message.

 Letter Assigned Number _ 0 A 1 B 2 C 3 D 4 E 5 F 6 G 7 H 8 I 9 J 10 K 11 L 12 M 13 N 14 O 15 P 16 Q 17 R 18 S 19 T 20 U 21 V 22 W 23 X 24 Y 25 Z 26