To determine the Natural Change for a country, one takes the country's birth rate minus the death rate, divided by 10. Norway's natural change would be 0.4. On the other hand, Pakistan's birth rate is 39, and their death rate is 11. Therefore, the natural change is 2.8. Migration also affects population change for a country.
Migration simply means, a change in residence that is intended to be permanent.
Generally, migration has economic causes and leads to a movement of people from poorer to richer countries. Population has been growing exponentially since the latter part of the 1700s. The exponential growth rate occurs if a population has a high birth rate through time and is never limited by famine or disease. Now we can use this information to figure out how long it will take a population to double if the same growth pattern continues. For example, the growth rate is 1.5 percent per year.