# Yottabyte

A yottabyte (derived from the SI prefix yotta-) is a unit of information or computer storage equal to one septillion (one long scale quadrillion) bytes. It is commonly abbreviated YB.

1 yottabyte = 1024 bytes = 1 000 000 000 000 000 000 000 000 bytes

It is a pleasant coincidence that Avogadro's number, 6.0221415×1023 is approximately equal to 279. That is, Avogadro's number is almost a "round number" in binary, and a (binary) yottabyte is approximately 2.01 × Avogadro's number of bytes. Humorously, it can be said that a (binary) yottabyte is about 2 moles of bytes.

How many yottabytes would it take to describe a single human being? Assuming the average adult human is 74.8 kg (165 pounds), we can determine a rough estimate of how many moles of atoms are in the human body. Since the body is made up of 65% oxygen, 18% carbon, 10% hydrogen, 3% nitrogen, 1.5% calcium, and other elements, one could use a periodic table to show that the average human body contains about 11 800 moles of atoms. If one would commit a single byte of information to store the location of every atom contained in the body of a human, it would require about 5 900 yottabytes! (One byte per atom would not actually be sufficient, however.)

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