An introduction to proof by contradiction, a powerful method of mathematical proof.
Follow this recipe for sieving numbers and see what interesting patterns emerge.
Take any prime number greater than 3 , square it and subtract one.
Working on the building blocks will help you to explain what is
special about your results.
Make a line of green and a line of yellow rods so that the lines
differ in length by one (a white rod)
All strange numbers are prime. Every one digit prime number is
strange and a number of two or more digits is strange if and only
if so are the two numbers obtained from it by omitting either. . . .
A game in which players take it in turns to choose a number. Can you block your opponent?
A man has 5 coins in his pocket. Given the clues, can you work out
what the coins are?
Using your knowledge of the properties of numbers, can you fill all the squares on the board?
Can you find a relationship between the number of dots on the
circle and the number of steps that will ensure that all points are