Question

You have a very big urn, and pebbles numbered with the natural numbers (1, 2, 3...). At time step 1, you put pebbles 1-10 in the urn. At time step 2, you take out pebble 1. At time step 3 you put in 11- 20. At time step 4 you take out pebble 2. 5-->put in 21-30. 6-->take out 3, etc. If you did this an infinite number of times, how many pebbles would be left in the urn? I like this problem a lot because even people with a strong math background will tend to get it wrong and defend their position vehemently. Hint: i didn't ask what the limit is as the number of time steps goes to infinity. I asked about if this was done an infinite number of times. Hint: are there more natural numbers or more even natural numbers?

Answer 1

Answer:

Not sure if I am correct but I do not think this is possible to answer. Because you consistently keep adding 10 and taking away 1. If you did this an infinite amount of time, the number would just keep growing. Not sure if I understood the question but that is my take.