Cards
with numbers 1, 2, 3, ... are put in
a box in a particular order.

One minute before noon numbers from
1 till 10 are put and a number 1 is
taken back.

1/2 minute before noon numbers from
11 till 20 are put and a number 2 is
taken back.

1/3 minute before noon numbers from
21 till 30 are put and a number 3 is
taken back.

And so on.

**How many numbers are in the
box at noon?**

**Answer:
none.**

We can consider any number, for example
number N. It will be taken back at N-th
operation. Let us look at the set:

It
is an "empty" set, and from
mathematical point of view there is
no paradox.

by
Tetyana Butler