Lower Secondary Big Button Page

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Hidden Treasures

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!
Calendar Capers link

Calendar Capers live

Stage: 3 Challenge Level: Challenge Level:1

Choose any three by three square of dates on a calendar page...

Counting Factors link

Counting Factors live

Stage: 3 Challenge Level: Challenge Level:2 Challenge Level:2

Is there an efficient way to work out how many factors a large number has?

Latin Numbers link

Latin Numbers live

Stage: 3 Challenge Level: Challenge Level:2 Challenge Level:2

Can you create a Latin Square from multiples of a six digit number?

Building Tetrahedra link

Building Tetrahedra live

Stage: 4 Challenge Level: Challenge Level:2 Challenge Level:2

Can you make a tetrahedron whose faces all have the same perimeter?

Gift of Gems link

Gift of Gems live

Stage: 4 Challenge Level: Challenge Level:2 Challenge Level:2

Four jewellers share their stock. Can you work out the relative values of their gems?

Rationals Between... link

Rationals Between... live

Stage: 4 Challenge Level: Challenge Level:2 Challenge Level:2

What fractions can you find between the square roots of 65 and 67?