factor30. According to your link 115m kilometers = 95m miles. This is wrong, using an approx of 1.6km per mile, 115m km = approx 70m miles. They also use paper thickness of 0.1mm which equals 0.00393", nearly 4 times thickness as my piece.
I'd work it out like this:
2^10 = 1000 (roughly)
so 2^50 = 1000^5
If the paper was 0.001 mm thick (I have to think in metric) one factor of 1000 would make it 1 mm. Two more factors of 1000 would make it 1 km. We are left with two factors of 1000. So the answer would be 1 million kilometres.
An inch is 25.4mm, increasing the answer to 25.4 million kilometres.
The approximation 2^10 = 1000 is 2.4% too small, so we need to increase the answer by 2.4% five times. This will be a bit more than 12% as it is compounded. Let's guess 12.5% becaue that is one-eighth i.e. about 3.2 million kilometres.