Help with letter puzzle

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azzey
Posts: 2
Joined: Thu 29 Dec, 2011 6:47 pm

Help with letter puzzle

Post by azzey » Thu 29 Dec, 2011 7:09 pm

I have this puzzle I'm working on. I'm not sure what kind of puzzle it is, but it may be initials of something in the UK. The puzzle was created some time between 1978 and 1995.

The letters form a sequence which I have to complete:

A
H
AA
BL
DU
HH
ME
SR
?

So far I've tried London underground stations, train stations, famous monuments and vehicle registration codes. BL could be British Library? The vehicle registration match the letters but I still can't solve the sequence. I'm not absolutely sure I'm on the right track so any assistance would be great!

Here's a website for the V-Reg codes: http://www.wolfbane.com/vreg.htm

Thanks.

ronald
Posts: 58
Joined: Tue 08 Mar, 2011 1:22 pm

Re: Help with letter puzzle

Post by ronald » Fri 30 Dec, 2011 7:34 am

I put the solution in three parts in case you want to try and figure each part for yourself.

For future reference, the source of the puzzle would be (by far) the best info to give.
azzey - You're lucky, this time.

First, a huge clue:
PRIME_BBCODE_SPOILER_SHOW PRIME_BBCODE_SPOILER:
Considering A = 1, B = 2, C= 3 ... helps to solve this

Obviously A = 1, H = 8.

Note, the sequence appears to be counting upward (the letters appear first in order of length, then in alphabetical order).
Then, the technique:
PRIME_BBCODE_SPOILER_SHOW PRIME_BBCODE_SPOILER:
Consider counting with the alphabet - but after Z = 26, you have AA = 27, AB = 28, AC = 29,... coincidentally, the same way that Microsoft Excel counts columns.

This is essentially then a 'Base 26' counting system, with 26s and Units - rather than Tens and Units

Then
AA = 1*26 + 1 = 27
BL = 2*26 + 12 = 64
DU = 4*26 + 21 = 125
and so on
Then, the solution:
PRIME_BBCODE_SPOILER_SHOW PRIME_BBCODE_SPOILER:
1,8,27,... are recognisably cube numbers (1 cubed, 2 cubed, 3 cubed, where 2 cubed = 2*2*2)

The answer is therefore 9 cubed = 729.

This is bigger than ZZ = 702, so we need a third letter (AAA = 703, AAB = 704,...).
The answer is ABA.

azzey
Posts: 2
Joined: Thu 29 Dec, 2011 6:47 pm

Re: Help with letter puzzle

Post by azzey » Fri 30 Dec, 2011 4:21 pm

ronald wrote:I put the solution in three parts in case you want to try and figure each part for yourself.

For future reference, the source of the puzzle would be (by far) the best info to give.
azzey - You're lucky, this time.
Thanks! The puzzle is embedded in a computer game, highly unlikely you know it as it's quite obscure.
ronald wrote: First, a huge clue:
PRIME_BBCODE_SPOILER_SHOW PRIME_BBCODE_SPOILER:
Considering A = 1, B = 2, C= 3 ... helps to solve this

Obviously A = 1, H = 8.

Note, the sequence appears to be counting upward (the letters appear first in order of length, then in alphabetical order).
Then, the technique:
PRIME_BBCODE_SPOILER_SHOW PRIME_BBCODE_SPOILER:
Consider counting with the alphabet - but after Z = 26, you have AA = 27, AB = 28, AC = 29,... coincidentally, the same way that Microsoft Excel counts columns.

This is essentially then a 'Base 26' counting system, with 26s and Units - rather than Tens and Units
I'd tried converting to a number system but had forgotten to try other bases. Duh! A very old trick. I should know better. I had used quite a few more complex mathematical systems on the numbers and modelled the values. It's always the simple things you miss.

Thank you again.

PuzzleScot
Site Admin
Posts: 2755
Joined: Fri 18 Jun, 2010 10:45 pm
Location: Edinburgh, Scotland

Re: Help with letter puzzle

Post by PuzzleScot » Fri 30 Dec, 2011 8:09 pm

Yeah, good work Ronald! well done. I also missed the base-26 option...

ronald
Posts: 58
Joined: Tue 08 Mar, 2011 1:22 pm

Re: Help with letter puzzle

Post by ronald » Sat 31 Dec, 2011 12:13 am

The puzzle is embedded in a computer game, highly unlikely you know it as it's quite obscure.
I'm curious now. I saw a single online reference to the same puzzle being in MUD2, but that doesn't quite match your dates.

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