Why when we are finding the average atomic mass we dont divide the abundance by 100? (for example the equation I use is: Average atomic mass= Abundance/100 x Percent mass.

Why does earth rotate? because earth is formed from cold gases collapsing due to gravity because the matter in the nebula that formed earth was spinning because earth forms more than 99% of the mass of the solar system because the hydrogen atoms inside the nebula fused to form helium