Big: Not the Tom Hanks One

So how big is big really? And how can you wrap your mind around the concept?  Let's start with the idea of water and some basic chemistry.  One mol of water, is 6.022 x 10²³  molecules of the stuff.  For a visual idea, not that it'll help much, that's 602,200,000,000,000,000,000,000 molecules of water.  That's a lot of water... or is it?  Actually that many water molecules is only about 18 grams of water, or a small sip.  Weird, all those molecules, and yet still such a small amount of water.  So here's the tricky part.  Imagine the following: oceans.  Yeah, that's a LOT of water molecules.

Let's try the math on this.  Every cubic milliliter or centimeter of water is 1.0 grams.  There are 133,800,000,000,000 cubic centimeters (and in turn milliliters) of water on earth at any given time.  So that's 1 gram per cubic centimeter, so 133,800,000,000,000 grams of water.  For reading, that's one hundred and thirty three trillion, eight hundred billion grams of water.  So, if there are 6.022x 10²³ molecules of water in ~18 grams, we can do the math.  133,800,000,000,000/18 = 7,433,333,331,111    So now multiply THAT number by the number of molecules of water in a mol, and you get (6.022x 10²³) x (7,433,333,331,111) = 4.4763533 x 10³⁶  molecules of water on earth at any given time.  Translated, 4,476,353,300,000,000,000,000,000,000,000,000,000
OR Four -Undecillion, four hundred and seventy six decillion, three hundred and fifty three nonillion, three octillion.  That's a lot of water molecules.