In approximately 24 hours, Santa will take off from the North Pole and begin delivering presents, all round the world.
Assuming he only visits the nice children, not the naughty ones, across the whole world, he has approximately 34 hours (added bonus of the different timezones) to visit 200 million children.
This means that he would have to travel at 4,705,882km/h, and spend 130 microseconds in each home.
This is all assuming constant work, and does not take into account breaks.
It has also been suggested that Santa uses quantum mechanics to allow him to be in multiple places at once: this is called superposition. It has been further suggested that he is aided by a sprinkle of fairy dust.
However he does it, Santa is guaranteed to work extremely hard tomorrow night to make everyone happy, so make sure you get to bed early to avoid being awake and risking him not visiting.
Until next time, keep calm and apply some Science!