To celebrate NRICH's 20th birthday, we've taken a look back in the archives and dusted off some problems from the early days, freshened them up, and added some new ideas. We hope you enjoy working on these hidden treasures!
problem
Calendar capers
Age
11 to 14
Challenge level
Choose any three by three square of dates on a calendar page...
problem
Favourite
Counting factors
Age
11 to 14
Challenge level
Is there an efficient way to work out how many factors a large number has?
problem
Favourite
Latin numbers
Age
14 to 16
Challenge level
Can you create a Latin Square from multiples of a six digit number?
problem
Building tetrahedra
Age
14 to 16
Challenge level
Can you make a tetrahedron whose faces all have the same perimeter?
problem
Gift of gems
Age
14 to 16
Challenge level
Four jewellers share their stock. Can you work out the relative values of their gems?
problem
Rationals between...
Age
14 to 16
Challenge level
What fractions can you find between the square roots of 65 and 67?
list
Introductions to ...
Age
11 to 14
Challenge level
This collection of articles gives introductions to important topics in mathematics
list
Thinking Mathematically - Secondary students
Age
11 to 14
Challenge level
A collection of resources aimed to help secondary students to think like mathematicians