Now it is eight times as thick as a single sheet. Three folds means eight times as thick. The answer is that it would reach past the sun. In math, the growth of the thickness is called exponential. Exponential growth means big things can happen quickly.
Technology sometimes changes exponentially.
The amount of information you can store on a hard drive in a computer or in the computer's memory both have changed exponentially. Every few years that number has doubled. That means that if a computer using the latest technology has 64 megabytes of RAM today, the same-priced computer for sale a few years ago probably had 32. A couple years before that, a comparable computer had 16. There is evidence that clocks, ground transportation, and air flight have all changed exponentially.