GCHQ Christmas Puzzle Solutions Part 3 Website

Website found here: https://www.gchqpuzzlebook.co.uk/erehsiegatstxenlaereht/

Password here: peyjigjxuzwiamwsgzrzggzk

This gives this puzzle:

176 142, 176 140!

146 18, 146 19, 130 64, 139 2, 299 4, 176 55, 146 5, 142 6, 176 15.

294 1, 285 9, 189 5, 285 13, 130 21, 156 2, 135 25, 273 6, 275 5, 294 4, 83 8, 125 4, 139 9, 148 11, 144 12, 132 13, 157 6, 156 7, 161 10, 134 2, 238 16, 238 17

Numbers are in pairs, the first of which are three digit numbers below 300. The second of which are factor dense numbers on the first and second rows but seem to be getting smaller.

Update! The GCHQ book has 303 main puzzles. taking the puzzle number and then the nth word from it gives:

Well done!

You have reached the final stage of the competition.

Now you should construct a wordbox as described in question one 5 six which contains all the letters of the Greek alphabet.

156 for reference

First solution 9x7

Better solution 8x7

Here's a link to the upper and lower bounds on the number of letters. I'm making the assumption that upsilon and epsilon share the string psilon:

https://docs.google.com/spreadsheets/d/1_0uJzrDDyNj4E_DvS-hFpMBPwvqdczulfbOI38XVRmI/edit?usp=drivesdk