Answer: Secret Code #180

The secret message says:

SUN

The shift was 22.

The secret note decoded: SUN
The note, decoded.

Letter by letter

Secret letterJOQ
Real letterNSU

Decode it with Python

This program does the decoding for you. Change the secret and the shift to crack other messages!

secret = "OQJ"
shift = 22
message = ""

for letter in secret:
    if letter.isalpha():
        number = (ord(letter) - ord("A") - shift) % 26
        message = message + chr(number + ord("A"))
    else:
        message = message + letter

print(message)

When you run it, it prints:

SUN

Did you know? Shift codes are very old. A Roman writer called Suetonius said that Julius Caesar wrote secret letters by shifting the alphabet by three. That’s why it’s often called the Caesar cipher.