To calculate growth rate, start by subtracting the past value from the current value. Then, divide that number by the past value. Finally, multiply your answer by 100 to express it as a percentage. For example, if the value of your company was $100 and now it's $200, first you'd subtract 100 from 200 and get 100. In exponential growth, a population's per capita (per individual) growth rate stays the same regardless of population size, making the population grow faster and faster as it gets larger. In nature, populations may grow exponentially for some period, but they will ultimately be limited by resource availability. Population projections are demographic tools that can be calculated with a formula based on current populations and growth rates. Because these rates can change due to adverse events or climate change, more accurate methods are needed for better projections.