Geocache formula solver

Put the values you've found on one line, as letters and numbers: A=3, B=7, C=12. Put the cache's formula on the next line, copied from the listing. The final appears as you type, with every substitution in the steps, the same point in decimal degrees and seconds, and links to open it in a map app.

Add values as you collect them. Until every letter has one, the steps say which are still needed, so you can check part of a formula on the way round.

Outside brackets, a letter is replaced by its digits: with A=3, 2A is 23, and with B=7, A.B is 3.7. Inside round or square brackets is a sum: (C+1) with C=12 is 13, and its digits take the brackets' place. Brackets can hold +, −, × or *, ÷ or /, and % for the remainder, and can nest.

N, S, E and W at the start of each half are the hemisphere, so N 52° and E 013° stay as they are. A letter E inside the numbers, as in 1E.000, is still a variable.

Inside brackets, two letters side by side are an error rather than a guess: write (A*B) to multiply, or move them outside the brackets to put their digits side by side.

With A=3, B=7 and C=12, N 52° 2A.B(C+1) becomes N 52° 23.713: 2 then A's 3, a point, B's 7, then C+1 = 13. E 013° 0(A+B).C5 becomes E 013° 010.125: 0, then A+B = 10, a point, then C's 12 and a 5. The steps list each of those, so a wrong value is easy to spot.

Most mistakes show up in the result. A minutes value of 60 or more can't be right, and the steps say so. A sum that doesn't come out whole, like (A/2) with A=7, is flagged too, since cache formulas are nearly always written to give whole numbers. Then check each value against the listing: a miscounted window or a misread date is the usual cause.

When the final is right, many owners add a checker. The puzzle lock makes one that works without a server.