  The paper compares probabilistic and exact methods for estimating the
asymptotic behavior of summation arithmetic functions, and estimates of the
results are obtained by precise methods. Conditions for stationarity in the
broad sense are investigated for summation arithmetic functions. A lemma and
theorems about the estimation of the standard deviation for the summation
arithmetic Mertens and Lowville functions completely satisfying the
stationarity conditions in the broad sense are proved.
