  The usual $\epsilon,\delta$-definition of the limit of a function (whether
presented at a rigorous or an intuitive level) requires a "candidate $L$" for
the limit value. Thus, we have to start our first calculus course with
"guessing" instead of "calculating". In this paper we criticize the method of
using calculators for the purpose of selecting candidates for $L$. We suggest
an alternative: a working formula for calculating the limit value L of a real
function in terms of infinitesimals. Our formula, if considered as a definition
of limit, is equivalent to the usual $\epsilon,\delta$-definition but does not
involve a candidate $L$ for the limit value. As a result, the Calculus becomes
to "calculate" again as it was originally designed to do.
