Uses of default arguments:
Default arguments are useful in such situations where some arguments almost always have the same value. For an example: bank interest may remain the same for all customers for a particular period of deposit.
The default arguments can be used to add new parameters to the existing functions. This increases the capability of a function by adding another argument. Using default arguments means that the existing function call can continue to use the old number of arguments, while new function calls can use more.
