real numbers are numbers. This simple fact can be asserted only if you
can accept an (actually) infinite expression for them.
This was accomplished in our mathematics, I think, approximately in the
XVII century, in a rich series of great mathematical achievements, from
analytic geometry to logarithmic/trigonometric computations. My question
is: who was the first to define or explicitly characterize the real number
by "an (actually) infinite sequence of decimal figures"?
Best wishes from a residual adriatic summer
Luigi Borzacchini