How is this JS code related to Euler Number

function PayyaInterest(amount, interest) {
  interest = interest * amount / 100;
  return "$" + (interest + amount);
}

//annual interest
let annualInterest = PayyaInterest(45, 100);


//6 months interest
let monthlyInterest = PayyaInterest(45, 50);

//another 6 month
let combinedInterest = monthlyInterest * 2;

console.log(annualInterest !== combinedInterest)