Abstract The out-of-time-order correlator (OTOC) is considered as a measure of quantum chaos. We formulate how to calculate the OTOC for quantum mechanics with a general Hamiltonian. We demonstrate explicit calculations of OTOCs for a harmonic oscillator. a particle in a one-dimensional box. https://www.ngetikin.com/mega-save-NHL-Calgary-Flames-Home-Jersey-iPhone-XR-Skin-p120897-hot-value/