What is the use of "eval()"

Question

In python
E.g input(eval())

Answer 1

I think to write an example:
eval("10 + 20")
print(eval) # 30

If you use eval(input("")), you'll can resolve a mathematical works

"eval is a built-in- function used in python, eval function parses the expression argument and evaluates it as a python expression. In simple words, the eval function evaluates the “String” like a python expression and returns the result as an integer."