adopted all over Europe almost at once, and in 
     consequence arithmetical calculations were immensely 
     accelerated. (p. 17)

     There then occurred an event that dramatizes the 
separation of letters and numbers in a most striking way. In 
Cultural Foundations of Industrial Civilization  (pp. 17­18), Nef 
cites the studies of Lucien Febvre concerning the sudden 
reversal in calculation, so that “the ancient habit of adding and 
subtracting from left to right, which still prevailed according to 
Lucien Lefebvre, until the end of the sixteenth century, began 
to be superseded by the much quicker way of making them 
from right to left.” That is to say that the separation of letters 
and numbers which had taken so long to achieve was finally 
accomplished by dropping the reading habit of left to right in 
the use of numbers. Nef spends time (p. 19) trying to resolve