Octane number 100 for Iso-Octane (2,2,4 – Trimethyl Pentane).
Octane Number can be defined as the percentage by volume of Iso-Octane in a mixture of Iso-Octane and n-Heptane which has the same antiknock qualities as the fuel under test.
Octane Number is used to know about Anti-Knock quality of the fuel.