# May, 2013

## What’s the difference between $x$ and $x_0$?

When you get to the co-ordinate geometry bit of C1, suddenly the equation of a line changes from $y = mx + c$ to $(y-y_0) = m(x - x_0)$. It doesn't really change - it's just another way of writing the same thing; especially when you're dealing with a

## Basic Maths Skills: How Estimating Saved Me Nearly \$30

It wasn't a big grocery run - in those days, I was a single bloke, living alone; a loaf of bread, a frozen pizza, a jar of coffee... "Dinner," as I called it. Oh and a few Lindt balls. You know them - the little chocolate balls you get at

## Silly Questions Amnesty

Surely you know the drill by now? You provide the questions. I provide the answers. All of it in the comments section below.

## The Mathematical Ninja’s Topological Takedown

"THIS." spat the Mathematical Ninja, "IS. THE. WORST. ARTICLE. I'VE. EVER. SEEN." It's a bad sign when the Mathematical Ninja starts talking in single-word sentences. I handed him an espresso. "What's wrong with it?" I asked. "I've not read it." "You don't want to!" said the Mathematical Ninja, slightly mollified.

## Logarithms revision quiz

You know the drill by now: answer some questions, see if you know your stuff. Just five questions this week.

## The Mathematical Ninja’s Guide To Roundish Numbers

"So that's 0.9332 times 500," said the student. Dubiously: "In your head?" "466.6," said the Mathematical Ninja, before the student could reach for his calculator. "Whoa," said the student, some seconds later, once he'd tapped in the sum and found the SD button. The student was new here. He was

## Silly Questions Amnesty

Mayday! Mayday! It's Mayday on Monday. Leave your mathematical distress calls in the comments below and I'll arrange a mathematical lifeboat for you.

## Wrong, But Useful: Episode 2

It's a new month, which means it must be time for a new episode of Wrong, But Useful! This time around, we talked about queuing at EuroDisney, how to play Battleships, why Peppa Pig's dad has a quadratic equation in his office, 110%, elliptic curves and Dave's brilliant new game.

## Sketching graphs: the DATA method

The DATA method is probably the coolest acronym I've ever come up with - it's even about graphs! It's a four-point plan for how to sketch a graph and be pretty sure of getting the salient features right. D is for domain The first thing to decide is, where is