Start by writing the number 1089 on a piece of paper and put it in your pocket. Now get someone to choose a three digit number where the last digit is at least 2 less than the first digit. Turn it round to form a new three digit number, then subtract it from the first one. For example, 481 − 184 = 297. Now turn the new number round to form a fourth three digit number, and add it to the third. 297 + ...

## Hypothesis testing made easy

Carrying out a hypothesis test often causes confusion. Here's how it works. Some hypothesis tests start with a known fact, such as "25% of patients treated for a particular disease will suffer side effects." A drug company may then claim that "a new treatment reduces the number of patients suffering side effects." The original figure, the status quo, is known as the "null hypothesis" and given the symbol H0. The new claim is called the "alternative hypothesis" and given the symbol ...

## Does division by zero = infinity?

Why should it? Well, try this: 5 ÷ 10 = 0.55 ÷ 1 = 55 ÷ 0.1 = 505 ÷ 0.01 = 5005 ÷ 0.001 = 5000 As we divide by smaller and smaller numbers the result gets ever bigger. Logically, then, as the divisor tends to (ie gets closer to) zero, so the result tends to infinity. But this is not the same as saying that division by zero actually is infinity, is it? What about drawing a graph with ...

## How to revise for your Maths exam…

Last month I made some suggestions for a revision plan. Now, having decided you're going to spend a 3 hour session revising Maths, how should you set about it? Since the only thing you will be asked to do in the exam is answer Maths questions, then surely the best way to revise is ... do lots of past paper questions! And you need to have the answers, or the mark scheme, to hand. But it's what you learn from answering ...

## Taking your IB Diploma? Here’s a revision plan…

I don't want to be too prescriptive about how you should revise – everyone's different, everyone remembers stuff in different ways – but you should definitely prepare a revision plan. If you don't, then it will be a matter of luck whether or not you'll be ready in time for the exams. Most of you will have at least some holiday time before the exams, and it's imperative you make the most of it – you're on your own, and it's ...

## A Mathematical Card Trick

Card tricks fall into several categories, and my favourite are those which look amazing but actually have some pretty simple maths behind them. Here's one of the simplest! 1. Take an ordinary pack of cards and shuffle it. Deal out 26 cards, face up, and remember the 7th card. 2. When you've dealt out the 26 cards, pick up the pile and turn them face down on the table, to one side. (If you're brave, shuffle them first, but make ...

## Help with your IB Mathematics

Whether you are in the first weeks of your diploma course, or whether you are halfway through, there are always going to be some parts of the maths syllabus that make you scratch your head! Over the past couple of years some of the blogs I have written have concentrated on specific topics which I know can benefit from further explanation. I thought it would be helpful to list those blogs here: a reference for those that are new to ...

## Games with Dots

Do people still play pencil and paper games these days? I grew up with them in my family – all sorts from number games, word games, drawing games. A number of the mathematical games involve spots or dots and, believe me, they can be fiendishly difficult to win against a good opponent. The simplest of all is boxes. A square grid of dots is created (the bigger you make it, the longer the game). The first player joins two adjacent dots with either ...

## MacTutor History of Mathematics

In my wanderings around the internet I came across a superb resource for anyone interested in, or needing information about, mathematicians, the history of mathematics, mathematical chronologies – even a 'famous curves' index. This is the MacTutor History of Mathematics site, created by John J. O'Connor and Edmund F. Robertson of the University of St. Andrews in Scotland. Under 'Mathematicians of the Day' there's an index of those who were born or died on every day of the year. I'm amazed ...

## What Do You Get Asked in University Interviews?

Some universities interview applicants. In the UK, the Oxford and Cambridge interviews are an important part of the application process, Imperial College and UCL tend to interview the majority of applicants. In the US, many Ivy League colleges also carry out interviews. But what should you expect, and how can you prepare? Interviewers stress that they are not testing knowledge, which would be unfair, given that applicants come from many different backgrounds and educational systems. The purpose, says Oxford, is to ...