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I've googled all the combinations I can, but haven't found an answer to this one, nor can I find it in any "related" StackOverflow Q&A's. In this sequence:

aaa = 1
aab = 2
aac = 3
aad = 4
aae = 5
...

what is the easiest way to convert any other string in the sequence (up to max "zzz") to a number, say "aem", or "svg" as random examples? Is there a spreadsheet formula to do this? (I'm a rudimentary user of LibreOffice Calc, FWIW.)

This must be simple for numerate people. :) Unfortunately, I'm somewhat literate, but not at all numerate! Any help with this appreciated!

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This is just base 26 with a as 0 and with 1 added to every number after converting it from base 26 to the target. Each letter is a digit. a=0 through z=25. From right to left, multiply the first digit by 1, the next by 26, the next by 26*26, etc. and add them up. I don't speak spreadsheet (aren't we supposed to be programmers here?) – Wumpus Q. Wumbley 13 mins ago

1 Answer

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I'm not sure which language do you use. Because you mentioned spreadsheet I assume that it's something like Excel. In Excel the formula should look like this:

=(CODE(TEXT)-97)*26*26+
 (CODE(RIGHT(LEFT(TEXT,2),1))-97)*26+
 (CODE(RIGHT(LEFT(TEXT,3),1))-97) +
 1

The first line is responsible for the first letter, the second for the second letter and the third for the last letter. In the last line there is +1 because the result would be computed from 0 not 1.

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