Better punctuation

Author: K-Sato1995

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

@@ -12,7 +12,7 @@ Imagine we need to write 1 billion. The obvious way is:
 let billion = 1000000000;
 ```
 
-But in real life we usually avoid writing a long string of zeroes as it's easy to mistype. Also, we are lazy. We will usually write something like `"1bn"` for a billion or `"7.3bn"` for 7 billion 300 million. The same is true for most large numbers.
+But in real life, we usually avoid writing a long string of zeroes as it's easy to mistype. Also, we are lazy. We will usually write something like `"1bn"` for a billion or `"7.3bn"` for 7 billion 300 million. The same is true for most large numbers.
 
 In JavaScript, we shorten a number by appending the letter `"e"` to the number and specifying the zeroes count: