I could generally find the logarithm of any number in a minute or two without the use of books or tables.
"A Budget of Paradoxes, Volume II (of II)"
Augustus de Morgan
"The wrong logarithm was taken, and of course that threw out all the calculations.
"Tom Swift and his Undersea Search or, The Treasure on the Floor of the Atlantic"
Victor Appleton
Had the missionaries been disposed to confer a real service on the Chinese, instead of misleading the world by their strange and wonderful accounts of this people; instead of bestowing so much time in translating into Chinese a set of logarithm tables for the use of Kaung-shee, the second Emperor of the present dynasty, of which they pretend he was so fond that he always carried them about with him suspended to his girdle, they should rather have taught them the use, and the convenience, of the Arabic numbers, of whose combinations and results their own language is not capable, and have instructed a few of their youth in the principles of arithmetic and the mathematics.
"Travels in China, Containing Descriptions, Observations, and Comparisons, Made and Collected in the Course of a Short Residence at the Imperial Palace of Yuen-Min-Yuen, and on a Subsequent Journey through the Country from Pekin to Canton"
John Barrow