You're A Mathematical Genius, You Know! by Murdo Macleod
... Let's see this process in action with a couple of examples: * * * Example 1 - Calculating the Dreaded Sales Tax The sales tax rate varies around the world, but here in the UK it's 17.5%. Urgh! What kind of figure is that? Let's look at it again and see how we can tame the beast by breaking it down. 17.5 It consists of 10, plus 5 plus 2.5, doesn't it? And those numbers form a distinct sequence. In other words "10, plus half, plus half again". Now that we know this, we can do something ...