So far you have learned about the rules that apply when using indices. But how might they be used in the real world? A good example is when bacteria divide and multiply – the population increases exponentially. The human population took 300,000 years to reach the first billion people, 130 years to add the second billion and only 12 years to add the fifth and sixth billion. We passed the seven billion mark last year. Find a table that shows the world’s human population and draw a graph using Excel, showing this data.