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?
Take any two digit number, for example 58. What do you have to do to reverse the order of the digits? Can you find a rule for reversing the order of digits for any two digit number?
Can you explain how this card trick works?
Daniel Loh (Age 10, Anglo-Chinese School,
Singapore) pointed out a fact about the way the numbers are placed
on dice. This is particularly important to remember if you don't
have any real ones to work with.
I have put everyone's solutions together into a table so that it
will be easy to check whether you have found a new one or not.
Kieran Davies (Age 10) & Carl
Jones (Age 9, Moorgate C.P. School) - 1 solution
Christina Ivanova (Age 11, Marlborough Primary
School) - 1 solution
Caroline Anderton & Sarah Peake (Year 7, The
Mount School, York) - 4 solutions
Leah Hathaway (Age 10) & Sophie Simpson (Age
11, Moorgate C.P. School) - 11 solutions
Edward Quantrill (Age 10, Tattingstone School) -
14 solutions - Well done!!