Work Out a Bill with a Service Charge in JavaScript

The challenge

Write bill(price, quantity) that returns the total cost plus a 10% service charge, rounded to 2 decimal places as a number.

Example

bill(40, 2)    // 88
bill(12.5, 3)  // 41.25

Write your answer below, then press Check my answer. Your code runs right here in your browser, and the tests tell you what works.

Your solution

It prints

Stuck? Open one hint at a time. Try again after each one.

Hint 1

The subtotal is price * quantity. Adding 10% is the same as multiplying by 1.1.

Hint 2

Math.round(x * 100) / 100 rounds to 2 decimal places and keeps it a number.

There’s always more than one right way. Read it, make sure you understand it, then try writing it yourself without looking.

Show one possible solution

Solution

function bill(price, quantity) {
  const total = price * quantity * 1.1;
  return Math.round(total * 100) / 100;
}

This exercise uses what Grade 3: Operators: Math, Comparisons & Logic teaches. Read those notes first if any of it is new.