Extensions can add focused helper methods to standard-library numeric types.

Add a number helper

numeric_extensions.swift
extension Int {
    func squared() -> Int {
        return self * self
    }
}

let base = 
let result = base.squared()
let message = "square=\(result)"

print(message)
extension Int {
    func squared() -> Int {
        return self * self
    }
}

let base = 
let result = base.squared()
let message = "square=\(result)"

print(message)
extension Int {
    func squared() -> Int {
        return self * self
    }
}

let base = 
let result = base.squared()
let message = "square=\(result)"

print(message)
standard type extension Extending a standard type keeps small domain helpers close to the type they operate on.