"Seeing
there is nothing that is so troublesome to mathematical practice, nor
that doth more molest and hinder calculators, than the multiplications,
divisions, square and cubical extractions of great numbers ... I began
therefore to consider in my mind by what certain and ready art I might
remove those hindrances."
Mirifici logarithmorum canonis descriptio (Napier)
"It
teaches (to speak in a word) the easy performance of all reckonings,
computations and accounts, without broken numbers [common fractions],
which can happen in man's business, in such a sort as that the four
principles of arithmetic, namely addition, subttraction, multiplication
and division, by whole numbers may satisfy these effects."
Introducing decimals in De Thiende (Stevinus)