# Hints

## 1. Calculate the interest rate

- You are expected to return a percentage.

## 2. Calculate the interest

- When calculating interest, it might be helpful to notice that `interest_rate` returns a percentage.
- You can use the function defined in the previous task (`interest_rate`) to calculate the interest.

## 3. Calculate the annual balance update

- When calculating the annual balance update, use the functions that have been defined in the previous steps.

## 4. Calculate the years before reaching the desired balance

- To calculate the years, one can keep looping until the desired balance is reached using a [`for`][for] loop.
- There is a special [operator][increment] to increment values by 1.

[for]: https://www.learncpp.com/cpp-tutorial/introduction-to-loops-and-while-statements/
[increment]: https://www.learncpp.com/cpp-tutorial/increment-decrement-operators-and-side-effects/