Practising a mathematical skill doesn't need to be tedious... dust off your angle, algebra and adding fractions skills, and put them to good use solving this set of problems!
problem
Favourite
Almost one
Age
11 to 14
Challenge level
Choose some fractions and add them together. Can you get close to 1?
problem
Favourite
Triangles in circles
Age
11 to 14
Challenge level
Can you find triangles on a 9-point circle? Can you work out their angles?
problem
Favourite
Cyclic quadrilaterals
Age
11 to 16
Challenge level
Draw some quadrilaterals on a 9-point circle and work out the angles. Is there a theorem?
problem
The simple life
Age
11 to 14
Challenge level
The answer is $5x+8y$... What was the question?
list
Hidden Treasures
Age
11 to 16
Challenge level
Try these treasures to celebrate NRICH's birthday!