2005 minus his half, and then minus the remaining half, until the 2005 one, ask the remaining number
It's the other third,
If it is, then the formula is 2005 * (1 / 2 * 2 / 3 * 3 / 4 *) 2004 / 2005), which can be continued in brackets, becomes 1 / 2005, so 1 is left
If you cut it by half, it will become 1 / 2, if you cut it by one third, it will become 2 / 3 If you subtract 1 / 2005, it becomes 2004 / 2005)