added a link to wikipedia

Author: Rnbsov

1-js/05-data-types/02-number/article.md

@@ -22,7 +22,7 @@ We also can use underscore `_` as the separator:
 let billion = 1_000_000_000;
 ```
 
-Here the underscore `_` plays the role of the "syntactic sugar", it makes the number more readable. The JavaScript engine simply ignores `_` between digits, so it's exactly the same one billion as above.
+Here the underscore `_` plays the role of the "[syntactic sugar](https://en.wikipedia.org/wiki/Syntactic_sugar)", it makes the number more readable. The JavaScript engine simply ignores `_` between digits, so it's exactly the same one billion as above.
 
 In real life though, we try to avoid writing long sequences of zeroes. We're too lazy for that. We'll try to write something like `"1bn"` for a billion or `"7.3bn"` for 7 billion 300 million. The same is true for most large numbers.