Seven billion people on earth

Acording to the United Nations, the earth's population has just reached seven billion. However, the United States Census Bureau estimates that, with the world’s population increasing by 215,120 a day, the figure of seven billion will be reached in about four months' time. The discrepancy in these two calculations shows how difficult it is to predict the entire population of the world accurately - it is impossible to say on what day we actually reach that figure, although it is safe to say we are nearing the seven billion mark, give or take a few million.