Atomic Mass Unit (amu) Definition:

A unit of measure equivalent to 1 g divided by Avogadro’s number.

Avogadro’s number: 6.02 X 10²³

Atomic Mass Unit (amu) Explained:

Avogadro’s number is the number of atoms in exactly 12 g of carbon. In other words, the value of 1 amu is defined with respent to C¹²