For all the people who think they are super-special - Yeah, I thought so too, but 2%, who can solve this, solve it WITHOUT any graphical or text representation. They are given facts and they have to solve it. So if you forget the right answer, go to isolated place and solve it only with your mind - then you are the 2%.
Hint on how to draw straight lines: Put a dot in the start of the line, then, while holding mouse button, right-click the screen and then click at the line's end. You get a perfectly straight line. If you can't see the point, where the line should end, try drawing from the end to the beginning.
Only one advice: if someone (not Natalie) died and you are low on revival items or it's a boss battle - use Natalie's skill, not items, because eventually you'll run out of them, and exactly next turn Natalie dies all the time.
Hint on completing the "guess-a-number" part. Try take take...90000 as a first number. If it says "too low" - number is between 90k and 100k. If it says "too high" - take 80000. Then repeat the cycle until you find X0k and Y0k points, that have the number between them. Once you get it - do the same with the second, third, fourth and fifth digitals of the number. Took me around one minute do it.