Question: how many atoms are there in the world ???????

Robert Woolfson answered on 15 Jun 2013:

Short answer – there are about 13 octodecillion atoms or 130,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 atoms in the world. In the universe as a whole there’s a lot more. For the universe as a whole, add another 30 or so zeroes on the end.

Long answer – There is a unit in chemistry called the mole, which tells us how many atoms are in a kg of stuff. It’s about 6 billion trillion atoms per kilogram. The world weighs around 5 thousand billion trillion kg. Using those two numbers together gives a lot of atoms.