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To Iff or Not to Iff?
In this feature you will find a selection of problems that will require you to reason logically. You will also be introduced to the symbols $\implies$ and $\iff$ and be challenged to use these to create true statements.
Plus magazine has a selection of interesting articles looking at logic, mathematical logic, its role in computer science and the philosophy of maths, and on how it's being used in applications.
River Crossing
Age 11 to 18
Challenge Level 
There is nothing half so much worth doing as simply messing about in boats...
Iffy Logic
Age 14 to 18
Challenge Level
Can you rearrange the cards to make a series of correct mathematical statements?
The Tour De Clochemerle
Age 14 to 18
Challenge Level
Can you work out where these 5 riders came in a not-quite-so-famous bike race?
Iff
Age 14 to 18
Challenge Level
Take a triangular number, multiply it by 8 and add 1. What is special about your answer? Can you prove it?
Mind Your Ps and Qs
Age 16 to 18
Challenge Level
Sort these mathematical propositions into a series of 8 correct statements.
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