Choose any three by three square of dates on a calendar page.
Circle any number on the top row, put a line through the other
numbers that are in the same row and column as your circled number.
Repeat this for a number of your choice from the second row. You
should now have just one number left on the bottom row, circle it.
Find the total for the three numbers circled. Compare this total
with the number in the centre of the square. What do you find? Can
you explain why this happens?
Make a set of numbers that use all the digits from 1 to 9, once and
once only. Add them up. The result is divisible by 9. Add each of
the digits in the new number. What is their sum? Now try some other
possibilities for yourself!
What happens to the perimeter of triangle ABC as the two smaller
circles change size and roll around inside the bigger circle?
The last ten Flibbins who live
on the planet Filbert are in trouble. They are under threat from a
cactus-like creature whose spines are fatal to the Flibbins and who
are due to start their annual moult in a few days time!!
The Flibbins have found a neighbouring planet that is
uninhabited and where they can survive if they can get there
safely. However, they have some problems with organising their
Firstly, they only have one spacecraft that will carry at most
three of them at a time.
Secondly, the ten Flibbins exist in pairs, (one red and one
blue) and blue Flibbins are very jealous of their red partners. So
jealous in fact, that they will not leave their red partners on
their own with any other bue Flibbin, no matter how serious their
situation (no wonder they are in danger of extinction!).
What is the quickest way of getting the five pairs of Flibbins
safely to the new planet?