Loop Tree Duality (LTD) is a method to rewrite Feynman integrals by applying the residue theorem to integrate out the energy component. The resulting integrals have convenient properties for numerical integration. In this talk I will describe LTD at one loop, and its generalization to multi-loops. I will show recent successes of numerically integrating a finite six-loop four-point function and a one-loop 2->3 amplitude using counterterms. Finally, I will discuss ongoing work to construct a suitable contour deformation. Along the way we will encounter NP-hard set problems and use concepts from geometry, dual numbers theory, and convex optimization.