In our usual calculus calculation, the extension from the infinitesimal to the infinitely great is defined as being infinitely close but not reachable, and the lessening from infinitely great to infinitesimal is also defined as being infinitely close and not reachable. From the definition of axiom 3 above, we know that this concept needs to be corrected. That is, if the superpositions of infinitesimal are gradually close to a certain quantity, then they can reach that quantity, and if the superpositions of infinitesimal cannot reach a certain quantity, then they are not close to that quantity.