Fixed a typo

snippets/primes.md

@@ -1,15 +1,14 @@
 ### primes 
 
-It generates primes till a given number ```m
-
-Explain briefly how the snippet works.
+It generates primes till a given number. 
 
+It works with the Sieve of Eratosthenes. It generate an array from 2 to the given number. Then it filters out the values (Using Array.filter()) divisible by any number from 2 to square root of the provided number.
 ```js
 const primes = num => {
   var arr =  Array.from({length:num-1}).map((x,i)=> i+2);
   var sqroot  = Math.floor(Math.sqrt(num));
-  var numsTillSqroot  = Array.from({length:numb-1}).map((x,i)=> i+2);
-  arra.forEach(x => arr = arr.filter(y => ((y%x)!==0)||(y== x)));
+  var numsTillSqroot  = Array.from({length:sqroot-1}).map((x,i)=> i+2);
+  numsTillSqroot.forEach(x => arr = arr.filter(y => ((y%x)!==0)||(y==x)));
   return arr; 
 }// primes(10) -> [2,3,5,7] 
 ```