Lord John Napier (1550-1617) from Merchiston (Scotland), thought to practice black arts, develops the Natural Logarithm (ln). He also invents a kind of mechanical calculator the famous Napier Bones and writes about it in his Rabdologica. Now it was rather simple to multiply. Bear in mind that in this period people hardly could divide and multiply, whence you could do that you belonged to the highest literate part of society.
John Napier makes as first use in print of the decimal point,
after it had been invented in the Netherlands, and invents logarithms,
and oals several means for multiplication. His best known implement however
is or are the so called "bones" this is an aid to multiplication.
But maybe the chessboard calculator is the most ingenious and least known!