I used to do that quite often, mentally. In fact, I am doing that now!  

Look at those legs, that is a great HIIT cardio work out 😁

Different periods, some areas up to 6 hours    An EOR spokesman told AFP that in El Salvador and Guatemala “the power outage (which occurred at 5:50 p.m. GMT) was brief.” In the case of Nicaragua, the EOR systems record that 35% of the energy system was recovered four hours after the incident, while Honduras recovered 95% in the same period. https://ticotimes.net/2019/09/16/system-failure-causes-power-outage-through-much-of-central-america

Here is another one:

How long did it take to come back up? No redundant systems in place?