d r a g g a b l e
You have 1000 $ to distribute in 10 envelopes
in order that when I ask you a whatever amount
(between 1 and 1000) you'll be able
to give me a certain number of envelopes
which will contain together the amount I've asked for
e.g. : If you put a 100$ in each envelope,
you will be able to give me 300$,
but if I ask you for 305$
you won't be able to give me that amount
without opening the envelopes!

Have fun !
click on the '=' sign in order to enter the last amount