HamStudy is the best one. The app cost a couple bucks but the mobile site is free

Also, I don’t agree with the OP and think it’s fucking dumb, but let’s not forget that “retard” used to be a medical term as well

I mean, sure. As someone who recently went back to school and is around a bunch of PhD and PhD students, they’re really, really smart… about their specific area of study. But more than some of them are fucking stupid when it comes to other, normal things

Not necessarily, a PhD isn’t a medical degree

A slightly easier way to think of this: leap years happen every 4 years, except that we skip one every 100 years (those that end in 00) unless it’s divisible by 400. So we had a leap year in 2000 because it’s divisible by 400, but 2100 will not be a leap year.