Many perturbative calculations in quantum field theories produce divergent series even after regularization. The pole mass of a quark is an example of problems that suffer from divergence series. This can be explained by the fact that the pole mass of a quark, i.e., the rest mass of an isolated quark, is not a physical quantity in a confining theory like QCD, thus the perturbative series for the pole mass need not converge. The large-order behaviour of perturbative calculation of the pole mass is governed by the so-called renormalons that are related to large or small momentum in loop integrals of Feynman diagrams. In this seminar, I discuss the leading renormalon of the pole mass and introduce a map to suppress this renormalon. This map reveals the structure of the leading renormalon in terms of coefficients of beta function and an overall normalization constant. Using the inverse of the map, I argue how the leading renormalon is generated and I obtain an explicit expression to calculate its overall normalization. Using this expression, I calculate the overall normalization of the leading renormalon of the pole mass for several values of quark flavors. Finally, I discuss the application of these results in extracting quark masses from experimental and lattice-QCD data.