You are sending messages to your allies, but you need to keep them secret from your enemies. You encode letters as numbers using:

A   B   C   D   ...   Z

0   1   2   3   ...   25

and the numbers are then altered using

Part 1

You have a coding machine. Your job is to input text, choose values for A and B and then get the coded messages. Good luck!

Code the message given to you by the teacher.

Part 2

Swap your message and values for A and B with a classmate, and try to decode the message by hand. First you must decide what 1/A is mod 26. Then decode using

Good luck!