I think this is a pretty hard question:
All the whole numbers from 1 to 2002, including the both of them, are written on a chalkboard in increasing order: 1, 2, 3... 2001, 2002. Then, the first number is erased, then the fourth number, then the seventh number, then the tenth number and so forth erasing all the numbers that occupy a place in the form 3k+1.
In the new list of numbers(after the first erasing) the same procedure is applied, erasing all the numbers occupying a place with the form 3k+1. This same process is repeated until all the numbers are erased from the chalkboard. What number is erased last?