Which books or what technique should be used to learn calculus perfectly and quickly?
Hey
Here are a few good books to prepare for Calculus for Engineering entrances like Jee Mains.
Differential and Integral Calculus N. Piskunov
Calculus and Analytic Geometry Thomas and Finney
Problems in Calculus by Sameer Bansal.
Problems in Calculus of One Variable by I.A.Maron
Best of luck