One Out One Under
Imagine a stack of cards, numbered one to seven in order, with one on the top.
Discard the top card (card 1) and put the next card (card 2) to the bottom of the stack.
Put out card 3 and then put card 4 under.
Continue putting one out and one under until you are holding only one card - it should be card 6.
-
What happens if you start with 8 cards ?
-
What happens if you start with 9 cards ?
-
How much can you find out about this situation ?
Send us whatever you discover.
Continue exploring until you can predict the final card and explain why your method works.
You may also like
Just Rolling Round
P is a point on the circumference of a circle radius r which rolls, without slipping, inside a circle of radius 2r. What is the locus of P?
Coke Machine
The coke machine in college takes 50 pence pieces. It also takes a certain foreign coin of traditional design...
Just Opposite
A and C are the opposite vertices of a square ABCD, and have coordinates (a,b) and (c,d), respectively. What are the coordinates of the vertices B and D? What is the area of the square?