Question

define calculas with practically example

Answer 1

A particular method or system of calculation or reasoning.
Any problem below is an example of it.

Answer 2

To evaluate a close answer about some question concerning a process we use large models: Example: For an area question one can tile the shape with 1 inch squares (our model of area) and try to match the overhang with interior voids based on best guess.
To get an exact area we do the same thing with smaller and smaller squares and add them up. In the limit as the square used for the tiling gets small enough, we are performing the integral process.
Calculus is the study of tools used for extremely small models