To find the smallest whole number of gallons needed to cover the entire wall, we need to calculate the total area of the wall in square feet.
Given that the wall is 12 meters tall and 80 meters long, we can calculate the area of the wall in square meters by multiplying the height by the length:
Area of the wall = height x length = 12 meters x 80 meters = 960 square meters
To convert the area from square meters to square feet, we need to multiply by the conversion factor:
1 square meter = 10.764 square feet
Therefore, the area of the wall in square feet is:
Area of the wall = 960 square meters x 10.764 square feet/square meter = 10,322.94 square feet
Since each gallon of paint covers 250 square feet, we can divide the total area of the wall by the coverage of one gallon to find the number of gallons needed:
Number of gallons = Area of the wall / Coverage per gallon = 10,322.94 square feet / 250 square feet = 41.29 gallons
Since we are looking for the smallest whole number of gallons, we need to round up to the nearest whole number. Therefore, you would need to buy at least 42 gallons of paint to have enough to cover the whole wall.