The Euler obstruction of a function f can be viewed as a generalization of the Milnor number for functions defined on singular spaces. In this work, using the Euler obstruction of a function, we give a version of the Lê-Greuel formula for germs f : (X, 0) → (C, 0) and g : (X, 0) → (C, 0) of analytic functions with isolated singularity at the origin. Using this formula and results of Loeser, we ...