How accurate are 4-, 6-, 8-, and 10-digit grids?

• A. 4-digit = 1,000 m square; 6-digit = 100 m square; 8-digit = 10 m square; 10-digit = 1 m square/GPS-level.
• B. All are 1 km squares
• C. 4-digit=10 m; 6-digit=1 m; 8-digit=0.1 m; 10-digit=0.01 m
• D. 4-digit=4 km; 6-digit=0.5 km; 8-digit=50 cm; 10-digit=5 cm

Answer: (A)

The idea being tested is how grid-reference precision scales as you add digits. Each pair of added digits refines the location by a factor of 10 on each axis, so the square size shrinks accordingly. A four-digit grid designates a 1,000 m by 1,000 m area (a 1 km square). Adding two more digits splits that into a 100 m by 100 m square. Adding another two digits gives a 10 m by 10 m square, and a final two digits narrows it to a 1 m by 1 m square. That progression matches the option stating 4-digit equals a 1,000 m square, 6-digit equals 100 m square, 8-digit equals 10 m square, and 10-digit equals 1 m square (GPS-level). The other choices misstate the actual square sizes or claim all grid levels share the same size, which isn’t how grid references sharpen location precision.