Big 1,000

This is a simple HTML game that is anything but simple!  The computer is thinking of a random number.

Level 1: 1-5

Level 2: 1-10

Level 3: 1-15

...this goes to level 1,000!  You read that right!  You'll never make it.

Due to a bug I'm trying to fix, level 1's answer is "0". I don't think any other level has 0 as an answer, but I've never been past level 18.