# The curvy line turned into a straight line!

You probably noticed the curvy line on the original graph turned into a straight line on the log transformed graph.

Why does this happen? Consider the following 2 facts:

1. In real life, every time 12 hours passes, the bacteria increase by a factor of 10.

2. In math life, every time you move up a log unit, you're increasing the magnitude of the original measurement by a factor of 10.

So, taking the log accounts for the multiplying nature of bacterial growth, and all you're left with on the graph is a straight line, pointing upwards.

When growth happens by multiplying the population by a constant number each timestep, we call that **
exponential growth**. And any time you have exponential growth, **taking the log of the population size will turn
the graph into a straight line**. This is true even if the constant multiplier is not 10 -- in that case, your straight line will
have a different slope, but it will still be straight.

Copyright University of Maryland, 2007

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