Tales of the unexpected
When working on mathematical tasks, you may sometimes discover unexpected results that take you by surprise. In this feature, we have chosen some problems that we hope will astonish and amaze you.
Subtraction Surprise Age 7 to 14
Challenge Level
Challenge Level
Try out some calculations. Are you surprised by the results?
Legs Eleven Age 11 to 14
Challenge Level
Challenge Level
Take any four digit number. Move the first digit to the end and move the rest along. Now add your two numbers. Did you get a multiple of 11?
Angles Inside Age 11 to 14
Challenge Level
Challenge Level
Draw some angles inside a rectangle. What do you notice? Can you prove it?
Triangle in a Triangle Age 14 to 16
Challenge Level
Challenge Level
Can you work out the fraction of the original triangle that is covered by the inner triangle?
Areas and Ratios Age 16 to 18
Challenge Level
Challenge Level
Do you have enough information to work out the area of the shaded quadrilateral?
Another Triangle in a Triangle Age 16 to 18
Challenge Level
Challenge Level
Can you work out the fraction of the original triangle that is covered by the green triangle?
Utter Chaos! Age 14 to 18
A small change can have a big effect! Read all about Chaos Theory in this short article.
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NRICH is part of the family of activities in the Millennium Mathematics Project.
NRICH is part of the family of activities in the Millennium Mathematics Project.