Thanks Bléro for this riddle
A new sort of waterlily has just been created by a laboratory.
These transgene waterlilies have the following properties:
In the pond of the laboratory, a waterlily doubles of surface every day, after 30 days it recover all the pond.
How long would it be necessary for 2 waterlilies to cover half of the surface of this pond?
Congratulations Patjol on his solution of the 06/15/04 but don't look at it, it's always better to find oneself...
If you want to see the (false) solutions which were sent to me.