Le Parisien: Quels sont les principaux diagnostics obligatoires pour louer son bien ?
The flow rate increases 100-fold (one hundred-fold) Would be a more idiomatic way of saying this, however, the questioner asks specifically about the original phrasing. The above Ngram search would suggest that a one hundred has always been less frequently used in written language and as such should probably be avoided. Your other suggestion of by one hundred times is definitely better than a ...
As you note, "percent" means "for every hundred," so there is nothing at all wrong with percent values greater than 100 when discussing proportions, e.g. profits increased by 120%. Like fractions, however, percent values are longer to express than multiples, so for values much greater than 100 you may hear them less frequently:
Learn how to juggle 3 balls with professional juggler Taylor Glenn! In-depth explanations, tips, and troubleshooting to help you learn to juggle like an awesome person. ...more
Juggling really is all about breaking something down to its simplest steps possible. Before you get the fun started you want to make sure that you have 3 juggling balls that are of equal size and weight. If you can find 3 balls of the same size and weight you’ll be good for the beginning.
Learn to juggle in 60 seconds or less by starting with a ball in your dominant hand, adding a second and third, and performing inside releases with eyes up. Master the basics of juggling with one ball and transition to the three-ball cascade by scooping from outside to inside and releasing at chest center, with peak timing.