pxt-calliope/docs/reference/js/lessons/looper/challenges.md

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2016-03-26 00:47:20 +01:00
# looper challenges
Coding challenges for the looper tutorial. #docs
## Before we get started
Complete the following guided tutorial:
* [tutorial](/microbit/lessons/looper/tutorial)
At the end of the tutorial, click `keep editing`. Your code should look like this:
```
for (let i = 0; i < 6; i++) {
basic.showNumber(i, 150)
basic.pause(2000)
}
```
### Challenge 1
### @video td/videos/looper-1
What if we want to count up to lucky number 7 instead? Let's do that by changing the ending value to `8` instead of `6`.
```
for (let i1 = 0; i1 < 8; i1++) {
basic.showNumber(i1, 150) // ***
basic.pause(2000)
}
```
* Run the program now to see your changes.
### Challenge 2
### @video td/videos/looper-2
What about 9? Let's do that by changing the ending value to `10`.
```
for (let i2 = 0; i2 < 10; i2++) {
basic.showNumber(i2, 150)
basic.pause(2000)
}
```
* Run your code to see the new counter.
### Challenge 3
### @video td/videos/looper-3
Now let's start counting from `3` instead! Our for loop will always start at `0` so we simply add `3` to the `i` variable when passing it to `basic->show number`.
```
for (let i3 = 0; i3 < 8; i3++) {
basic.showNumber(i3 + 3, 150) // ***
basic.pause(2000)
}
```
Run it on the simulator!
### Challenge 4
### @video td/videos/looper-4
Now, let's **count down from 9**. Change the line `basic->show number(i + 3, 150)` to `basic->show number(9 - i, 150)`.
```
for (let i4 = 0; i4 < 10; i4++) {
basic.showNumber(9 - i4, 150) // ***
basic.pause(2000)
}
```
* Run the code to make sure it is doing what is expected.
### Challenge 5
After counting down from `9` let's show the string `BOOOM`!