When writing programs, it is important to create ways for the user to interact with the program.
In Javascript, we can use the `prompt()` function to get data from the user.
```javascript
var name = prompt("What is your name?")
console.log("Hello, " + name)
```
> NOTE: You probably want to go to `Settings` and turn off `AutoUpdate` so it doesn't run your code every time you make a change
The `prompt()` function will show an input in the user's browser and then return that value.
By default, the `prompt()` function will return a string. This is great, but you may need to convert the string to a number or another data type.
You can convert one variable to another using any of the following functions, depending on the type of data you want:
- `String()`
- `Number()`
- `Boolean()`
For example, if you wanted to get the user's age as a number, you could use the `Number()` function:
```javascript
var ageInput = prompt("How old are you?")
var ageAsNumber = Number(age_input)
var timeTilRetirement = 65 - ageAsNumber
console.log("You will maybe be able to retire in " + String(time_til_retirement) + " years.")
```
Notice how we used `String()` to convert the number back into a string before we could combine it with the other text?
We could have made our code shorter if we had written something like this:
```javascript
var age = Number(prompt("How old are you?"))
```
That would immediately convert the input into a number, but maybe would have been harder to understand when you read the code.
## instructions
Complete each of the following challenges using variables, operators, `prompt()`, and `console.log()`.
**Challenge 1**
> Create a program that takes in a First Name, Last Name, and Age, and tells them how old they are in months.
>
> For example:
> ```plaintext
> Hello Joe Smith, you are 336 months old.
> ```
**Challenge 2**
> Create a program that takes in the sides `a` and `b` of a right triangle and prints out the length of the hypotenuse.
> Remember the pythagorean theorem:
> $
> a^2 + b^2 = c^2
> $
**Challenge 3**
> You just got home from a trip around South America and have a few different currencies:
> - Colombian Pesos
> - Peruvian Soles
> - Brazilian Reais
>
> Write a program that takes in each currency, converts them to USD, and prints out the total value.