## On the Subject of Caesar’s Maths

You thought maths was hard enough? Well now it’s encrypted too.

• This module will display three LEDs and a maths question, encrypted using a Caesar Shift cipher.
• Use the formula below to determine the shift key.
• Decipher the question using the concise table on the next page.
• Select the button with the correct answer to the problem.
• If the answer is a decimal, round down to the nearest integer.
• Choosing an incorrect answer will cause a strike and reset the module.

### Caesar Shift key formula:

((6a * bc) - d) mod 26

a = sum of digits in the serial number

b = number of batteries on the bomb + 3

c = number of green LEDs on the module

d = number of red LEDs on the module

### Cipher translation table:

The top row shows the encrypted letter, and the left-hand column shows the shift key. The intersection will give the decrypted letter.

Shift keyABCDEFGHIJKLMNOPQRSTUVWXYZ
0abcdefghijklmnopqrstuvwxyz
1zabcdefghijklmnopqrstuvwxy
2yzabcdefghijklmnopqrstuvwx
3xyzabcdefghijklmnopqrstuvw
4wxyzabcdefghijklmnopqrstuv
5vwxyzabcdefghijklmnopqrstu
6uvwxyzabcdefghijklmnopqrst
7tuvwxyzabcdefghijklmnopqrs
8stuvwxyzabcdefghijklmnopqr
9rstuvwxyzabcdefghijklmnopq
10qrstuvwxyzabcdefghijklmnop
11pqrstuvwxyzabcdefghijklmno
12opqrstuvwxyzabcdefghijklmn
13nopqrstuvwxyzabcdefghijklm
14mnopqrstuvwxyzabcdefghijkl
15lmnopqrstuvwxyzabcdefghijk
16klmnopqrstuvwxyzabcdefghij
17jklmnopqrstuvwxyzabcdefghi
18ijklmnopqrstuvwxyzabcdefgh
19hijklmnopqrstuvwxyzabcdefg
20ghijklmnopqrstuvwxyzabcdef
21fghijklmnopqrstuvwxyzabcde
22efghijklmnopqrstuvwxyzabcd
23defghijklmnopqrstuvwxyzabc
24cdefghijklmnopqrstuvwxyzab
25bcdefghijklmnopqrstuvwxyza