And now for something completely different. (Not if you were paying attention last year of course, or the year before that, but we are not sure how many of you even noticed that we were running a Sunday puzzle thread, so we thought it best to assume you hadn’t.)

With the joy of the recent series of Ludwig sadly behind us, Harry and the Elves will be putting on their thinking caps (otherwise known as deer-stalkers) and trying to find some puzzles for you to enjoy over your (insert beverage of choice here) on a Sunday morning. We will publish a solution alongside next week’s puzzle, but if you want to post your own solution to the forum, feel free! We won’t publish those posts until the solution is revealed so you won’t be spoiling it for anyone else and you will be claiming credit!

Turning DATA into FACTS

Here in the training section at BOSS, you are more used to turning numbers into letters. But there is no rule in real life that says intercepted messages will always arrive in that form.

Here is a short puzzle that landed on our desks from our friends in the City of London Police. One of their targets had been stealing from an employer and keeping records of the thefts. They thought they were being clever by using a code to disguise the transactions, but a sharp-eyed young officer who trained with us spotted the following calculation in one of the records and was able to use it to crack the cipher.

They wondered whether you would like to try it too.

The puzzle

Need a hint?

If you need a hint then click here to reveal it,, but we would really suggest trying the puzzle on your own first!

Hint 1

A four-digit number added to itself has produced a five-digit number, what does that tell you about $F$?

Hint 2

Look carefully at the tens column.

If $c_1$ is the carry from the units column and $c_2$ is the carry into the hundreds column, then

$$T+T+c_1=T+10c_2.$$

There are only two ways that can happen. What are they?

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