pxt-calliope/docs/lessons/digi-yoyo/challenges.md
Sam El-Husseini e3975e65e5 pxt-microbit Accessibility PR (#529)
* Accessibility changes
2017-09-07 13:42:08 -07:00

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# digi yoyo challenges
Coding challenges for the digi yoyo.
## Before we get started
Complete the following [guided tutorial](/lessons/digi-yoyo/activity), your code should look like this:
```blocks
let count = 0;
while (count < 10) {
basic.pause(100);
basic.showNumber(count);
count = count + 1;
basic.pause(20);
}
```
## Challenge 1
How about we create a counter that counts backwards from 10 to 1? Let's add a while loop that executes only when `count` is greater than 0.
```blocks
let count = 0;
while (count < 10) {
basic.pause(100);
basic.showNumber(count);
count = count + 1;
basic.pause(20);
}
while (count > 0) {
}
```
## Challenge 2
Inside of the while loop, let's add `pause->(1000)` so that we have a pause between each number as it's counting down. Also, let's show `count`!
```blocks
let count = 0;
while (count < 10) {
basic.pause(100);
basic.showNumber(count);
count = count + 1;
}
while (count > 0) {
basic.pause(100);
basic.showNumber(count);
}
```
* Run the code to see if it works as expected.
## Challenge 3
Now, we need `count` to decrease by one after the @boardname@ has displayed the value of `count`.
We can do this by adding this line:
```blocks
let count = 0;
count = count + (count - 1);
```