Basic math help-- me dumb

<p>This is for APES-- a formula would be great </p>

<p>A country currently has a population of 100 million and an annual growth rate of 3.5%. If the growth rate remains constant, what will be the population of this country in 40 years?</p>

<p>100,000,000(1.035)^40</p>

<p>But don’t trust me, I’ve been wrong umpteen times today.</p>

<p>Population(1.(Growth Rate))^Years</p>

<p>thats right, but i need a way to do it without a calculator</p>

<p>Turn it into a rough fraction. For example, you can turn 11% into roughly 11 over 10</p>