I just learned the astonishing fact that Tenth-Century Pope Sylvester II personally introduced into Western Europe both Arabic (Hindi) numerals and the abacus. He had learned about this (at the time) new mathematics technology while visiting Moorish Spain prior to his elevation to the Vatican.
Even the simplest arithmetic is extremely difficult with Roman numerals, which, of course, also do not include "zero" (see "A Short History of Zero" by Lawrence Murray). His further work as Pontiff in fostering scientific and mathematics education earned him the sobriquet "Scientist Pope" - as reported in D.L. Lewis's fascinating new book (2008), God's Crucible: Islam and the Making of Europe, 570-1215 (pg 329).
Dark Age Europe was indeed primitive, violent, and chaotic, but there were occasional glimmers of light. The Roman Catholic Papacy has had an, at times, deserved reputation for thwarting the advance of science, a premier example being the prosecution of Galileo. But the record on science and mathematics is varied.