This unit’s material includes three very separate topics. We begin with numerical integration – another of the most important numerical methods we glance at in first year (together with Newton’s method, linear approximation, and – soon – Taylor polynomials). The next section covers an interesting detail, looking at integrals that misbehave, either by having an unbounded integrand or an unbounded interval. Either way, the solution is to use limits. Finally, we begin to study differential equations, which are the basis for a tremendous amount of engineering.