const calculator = {
  value: 10,
  add: function(x) {
    return this.value + x;
  },
  multiply: function(x) {
    return this.value * x;
  }
};

const add5 = calculator.add;
const double = calculator.multiply.bind(calculator);
const triple = calculator.multiply.bind({value: 3});

console.log(add5(2) + double(3) + triple(4));