const name = "John"
const lastName = "Doe"
const fullName = name + " " + lastName 
// "John" + "Doe" = "JohnDoe" // "John" + " " + "Doe" = "John Doe"
// concatenation
console.log(fullName)

// number
const a = 5
const b = 10
const c = a + b
console.log(c)