Daily Coding Challenge - Streaming Cost

Ninge3007 · June 18, 2026, 8:15am

Tell us what’s happening:

I think the solution that some of the tests want is wrong.
e.g. the solution in Test 2 is “$12.73” but the unrounded price is “12.735” so when I round it, it becomes “12.74” which doesn’t count.
And when I use Math.floor() other tests fail.

Your code so far

const rent = {
  "HD": 3.99,
  "4K": 5.99
}
const buy = {
  "HD": 12.99,
  "4K": 19.99
}

function getStreamingBill(cart, subscription) {
  let price = 0;
  for (const movies of cart){
    price += (movies["type"] == "buy") ? buy[movies["format"]] : rent[movies["format"]];
  }

  switch(subscription){
    case "basic":
      price = price * 0.9;
      break;
    case "premium":
      price = price * 0.75;
      break;
  }

  return `$${Math.round(price * 100) / 100}`;
}

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:151.0) Gecko/20100101 Firefox/151.0

Challenge Information:

Daily Coding Challenge - Streaming Cost

https://www.freecodecamp.org/learn/daily-coding-challenge/2026-06-18

GitHub Link: https://github.com/freeCodeCamp/freeCodeCamp/blob/main/curriculum/challenges/english/blocks/daily-coding-challenge/6a15cadf5f240d05a2649556.md

ILM · June 18, 2026, 8:33am

I have opened this issue about this, thank you for reporting

github.com/freeCodeCamp/freeCodeCamp

Daily Coding Challenge 312 (Streaming Cost): test cases land on half-cent rounding boundaries

opened 08:33AM - 18 Jun 26 UTC

majestic-owl448

scope: curriculum status: waiting triage daily coding challenge

### Describe the Issue Daily Coding Challenge 312 ("Streaming Cost") has test c…ases whose expected outputs land on a half-cent rounding boundary, so the "correct" answer depends on the rounding method and the order of operations rather than on any well-defined rule. Three of the six tests are affected: | Test | Inputs | True total | Expected | `Math.round` (round half up) | Sum-then-multiply | | - | - | - | - | - | - | | 2 | `[HD rent, HD buy]`, `premium` | 16.98 × 0.75 = **12.735** | `$12.73` | `$12.74` | `$12.73` | | 4 | `[4K buy, 4K buy]`, `premium` | 39.98 × 0.75 = **29.985** | `$29.98` | `$29.99` | `$29.98` | | 6 | `[HD rent, 4K rent, HD buy, 4K buy, HD buy]`, `basic` | 55.95 × 0.9 = **50.355** | `$50.36` | `$50.36` | `$50.35` | Why this happens: - The description says "rounded to two decimal places", which a learner reasonably implements as round-half-up via `Math.round(price * 100) / 100`. But `16.98 * 0.75` is stored in IEEE-754 as `12.734999999999999432`, so `Math.round(... * 100) / 100` yields `12.74` while the reference solution's `toFixed(2)` (and Python's `f"{:.2f}"`) yields `12.73`. The expected output only matches because the reference solution happens to use `toFixed`, which silently relies on the floating-point representation rather than on a defined rounding rule. The learner's answer is arguably the more mathematically correct one. - Test 6 is broken even without changing the rounding method: accumulating per item (what the reference solution does) gives `50.355000000000004 → 50.36`, but summing first and then applying the discount, both using `toFixed`/`.2f`, gives `50.355 → 50.35`. Two equally valid implementations of the same approach disagree. This affects both the JavaScript and the Python versions, which share the same challenge ID and the same expected outputs. ### Affected Page https://www.freecodecamp.org/learn/daily-coding-challenge/2026-06-18 ### Your code ```js function getStreamingBill(cart, subscription) { let price = 0; for (const movies of cart) { price += (movies["type"] == "buy") ? buy[movies["format"]] : rent[movies["format"]]; } switch (subscription) { case "basic": price = price * 0.9; break; case "premium": price = price * 0.75; break; } return `$${Math.round(price * 100) / 100}`; } ``` ### Expected behavior The test inputs should be chosen so no total lands on a half-cent boundary (i.e. the third decimal of the discounted total is clearly 0-4 or 6-9), making the expected output independent of the rounding method and the order of operations. The JavaScript and Python versions must be updated in lockstep so they keep the same inputs and expected outputs. ### Screenshots N/A ### System - Device: Laptop - OS: N/A - Browser: N/A - Version: N/A ### Additional context Source files: - JavaScript: https://github.com/freeCodeCamp/freeCodeCamp/blob/5a0247f95f5cb675a4409f2eb22603e16eaf4401/curriculum/challenges/english/blocks/daily-coding-challenges-javascript/6a15cadf5f240d05a2649556.md#L35-L62 - Python: https://github.com/freeCodeCamp/freeCodeCamp/blob/5a0247f95f5cb675a4409f2eb22603e16eaf4401/curriculum/challenges/english/blocks/daily-coding-challenges-python/6a15cadf5f240d05a2649556.md#L38-L80

Topic		Replies	Views
Exact Change exercise, why the floating point error and best approach to subtract integer from floating point?	12	7740	October 5, 2020
Don't understand why numbers add up weird	1	613	November 12, 2017
Exact Change - the fifth test	6	1180	March 27, 2017
How to make the '0' digit	9	768	May 21, 2020
Cash Register -help	3	684	June 2, 2020

Daily Coding Challenge - Streaming Cost

Tell us what’s happening:

Your code so far

Your browser information:

Challenge Information:

Related topics