GPS Treasure Hunt Math: Coordinate Formats, Distances & Bearings, Waypoint Projection, Puzzle Checksums and Multi-Stage Final Coordinates

What you'll build

What you will be able to do

Each lab ends with a concrete result that you build yourself and the checker confirms, cell by cell.

• Turn five decimal latitudes into degrees and decimal minutes, write them as clean labels with TEXT, find the seconds of the DMS format with MOD and convert four west longitudes back into signed decimal degrees.
• Work out how many metres one minute, a tenth, a hundredth and a thousandth of a minute stand for north–south and east–west at the hunt's latitude, and turn a 25 m search radius into thousandths of a minute.
• Split five legs into kilometres north and east, combine them into a flat distance with SQRT and compare it with the haversine distance on a sphere.
• Turn six legs into bearings with ATAN, correct the quadrant by hand instead of using ATAN2, keep every bearing between 0° and 360° with MOD, name the compass point and work out the back bearing.
• Project four new waypoints from Ida's start point using a distance in metres and a bearing: the change in latitude and longitude with COS and SIN, then the new decimal coordinates.
• Split clue numbers into digits with INT and MOD to get digit sums and digital roots, look up letter values A = 1 … Z = 26 in a table and add up the value of the riddle's answer word.
• Feed the values found at three stages into the puzzle's final formula, get the final minutes of latitude and longitude, measure the distance from the start with the flat rule and check that the final lies inside the promised radius.
• Measure how far one wrong digit moves Ida's final, then summarise the club's 16-hunt log by difficulty with COUNTIFS and COUNTIF and chart the find rate per difficulty.