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problem
Please explain
11 to 14
Visitors to Earth from the distant planet of Zub-Zorna were amazed when they found out that when the digits in this multiplication were reversed, the answer was the same! Find a way to explain why this works.
problem
Circle box
14 to 16
It is obvious that we can fit four circles of diameter 1 unit in a square of side 2 without overlapping. What is the smallest square into which we can fit 3 circles of diameter 1 unit?
problem
Hexagon line
11 to 14
How many hexagons are required for the perimeter of the whole shape to have length 1002cm?
problem
Favourite
An easy way to multiply by 10?
7 to 11
Do you agree with Badger's statements? Is Badger's reasoning 'watertight'? Why or why not?
problem
Favourite
Number lines in disguise
7 to 14
Some of the numbers have fallen off Becky's number line. Can you figure out what they were?
problem
Sum one special
11 to 14
Three different integers have a sum of 1 and a product of 36 - what are they?
problem
Pentakite
14 to 18
Given a regular pentagon, can you find the distance between two non-adjacent vertices?
problem
A brief introduction to complex numbers
14 to 18
In this problem, we define complex numbers and invite you to explore what happens when you add and multiply them.
problem
A brief introduction to the Argand diagram
14 to 18
Complex numbers can be represented graphically using an Argand diagram. This problem explains more...