Using 5.9 pb(-1) of e(+)e(-) annihilation data collected at center-of-mass energies from 3.640 to 3.701 GeV with the BESIII detector at the BEPCII Collider, we measure the observed cross sections of e(+)e(-) -> (KSX)-X-0 (where X = anything). From a fit to these observed cross sections with the sum of continuum and psi(3686) and J/psi Breit-Wigner functions and considering initial state radiation and the BEPCII beam energy spread, we obtain for the first time the product of psi(3686) leptonic width and inclusive decay Physics Letters 820 (2021) 136576 branching fraction Gamma B-ee(psi)(3686)(psi(3686) -> (KSX)-X-0) = (373.8 +/- 6.7 +/- 20.0) eV, and assuming Gamma(ee)(psi)((3686)) is (2.33 +/- 0.04) keV from PDG value, we measure B(psi(3686) ->(KSX)-X-0) = (16.04 +/- 0.29 +/- 0.90)%, where the first uncertainty is statistical and the second is systematic.