Final answer:
When reading a grid reference on a map, the eastings number is read first, followed by the northings. A. Eastings correspond to the east-west position, similar to longitude, while northings give the north-south position akin to latitude.
Step-by-step explanation:
When reading a grid reference number corresponding to a grid on a map, you read the eastings number first. The eastings are the lines running from the south to the north, but they are used to determine a position in the east-west direction. This means that you would give the east-west coordinate before the north-south one, which is known as the northings. The concept is similar to how you would read the x-coordinate first in a Cartesian coordinate system, where the x-axis represents the east-west direction and the y-axis represents the north-south direction.
Remember that just as a geometric grid uses coordinates to define points in space, a geographical grid made up of lines of latitude and longitude provides an address for any location on Earth. Latitude provides the north-south position, while longitude gives the east-west position. Hence, when you read maps and grid references, eastings is akin to longitude (east-west position) and is read before northings, which is similar to latitude (north-south position).