When people say there’s been an “𝑥 fold increase in such and such.” They mean such and such is 𝑥 times as big.
If you get something that actually folds like a sheet of paper, the amount of layers doubles each time. One fold = twice as many layers. Two folds = four times as many layers…
Must the fold be exactly in half?
What if I just fold a tiny corner over?
That would still be two layers. Although folding all the corners would allow four fold to equal two.