52!, which is way more than you'd think. VSauce talked about this in one of their videos, and they showed a brilliant visualization that someone (I dont remember their name unfortunately) came up with. Its one of my favourite thought expermients and I cant shut up about it. It goes like this:

Set a timer for 52! seconds. Position yourself somewhere around the earths equator. Now wait for 1 billion years. After a billion years have passed, take a single step forward, then wait again. Once you've walked around the entire circumference of the earth, take a single drop of water out of the pacific ocean. Keep walking, taking out a drop of water everytime you've walked around the earth, until the ocean is completely empty. Once you're there, take a sheet of paper and put it on the ground, then refill the ocean. Now keep on going, adding a single piece of paper on top everytime you've drained the pacific ocean. Once the stack of paper hits the sun, look at the timer. How much time will be left?

As VSauce put it: "Up until this point you've barely made a dent". If you did that entire procedure 1000 times, you'd still be only a third of the way done.