Mr. J Gallagher

Substitution Code Breaking

NAME: ______

The following messages have been put into a code using numbers for letters – the table below shows how to decode each number to its corresponding letter.

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

i.e. 1 decodes as A, 2 decodes as B etc.

The following are the values for p, q, r, s, t and u:

Letter in expression / Value / Letter in expression / Value
p / 3 / s / -2
q / 4 / t / -1
r / 5 / u / 2

With this information – can you now decode the messages?

Example: r – u = 5 – 2 = 3, so r – u decodes as C

1.

q2 – p / p + s / r2 – r / 3p – t / 4q + p / p + q – s / 2(q + r) – t
-3t / 3r / 2(p + q) – t / - ups

2.

qr + p / pr / uqr / pr – p / qu – s2 / p / 3pq / q2
u – t / u3 / u + t / ur + p / q2 / (u – t)2 / r (u – t) / 2pq / qr + t

3.

p + q / p2 / qr + u / p – s / 3pq / 2(q + r) – t
q2 – p / 3r / uqr / p - s
ru + s / 2(p + q) – t / q2 – p / r / qr + p / 3r / uqr / r + up

1