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.diegojavierfares.com/bargain-Merlin-the-Magical-Wizard-Boys-Costume-special-save/