Population density of a city is obtained by dividing the total population of a city by its area. Population density = Population/Area We have been provided the population density and the total population of Manila. So, we can calculate the total area of Manila using the equation below, derived from the equation above. Area = Population/Population Density Area = 1,652,171/111,002 Area = 14.8841552404 square miles Rounding up to the nearest tenth of a square mile, we have. Area = 14.9 square miles.