SyntaxError: missing formal parameter( )

function square(3) {
  return number * number;
};
// SyntaxError:   

function greet("Howdy") {
  return greeting;
};
// SyntaxError:   

function log({ obj: "value"}) {
  console.log(arg)
};
// SyntaxError:   

function square(number) {
  return number * number;
}

function greet(greeting) {
  return greeting;
}

function log(arg) {
  console.log(arg);
}

square(2); // 4

greet("Howdy"); // "Howdy"

log({ obj: "value" }); // Object { obj: "value" }