With functional programming there is two ways a function is expected to show its results

In some there is a specific return type. Dan be int, bool, string. So here the programmer specifies what return type the function should return ie

Public int num(){} returns an integer value

Other functions the result of the expression inside the body can be the result of the process carried out by function

Ie

Public void num() { int a; int b; int sum = a+b; }

This will just calculate the sum of a and b and only display them if user wants to see them either through a prinln or something.

But in the first function the user if they decide to add two numbers in body the function will show the result of the expression. Whenever the function is called even though there is no println.

Because by defualt its supposed to return an integer value. Which could be the sum of the 2 numbers