fixes

1-js/02-first-steps/06-type-conversions/1-primitive-conversions-questions/task.md

@@ -11,7 +11,7 @@ What are results of these expressions?
 "" - 1 + 0
 true + false
 6 / "3"
-2" * "3"
+"2" * "3"
 4 + 5 + "px"
 "$" + 4 + 5
 "4" - 2

1-js/02-first-steps/07-operators/article.md

@@ -234,7 +234,9 @@ alert( 4 ** (1/2) ); // 2 (power of 1/2 is the same as a square root, that's mat
 alert( 8 ** (1/3) ); // 2 (power of 1/3 is the same as a cubic root)
 ```
 
-## Increment/decrement: ++, --
+## Increment/decrement
+
+<!-- Can't use -- in title, because built-in parse turns it into – -->
 
 Increasing or decreasing a number by one is among the most common numerical operations.
 

1-js/02-first-steps/08-comparison/article.md

@@ -180,7 +180,7 @@ The reason is that an equality check `==` and comparisons `> < >= <=` work diffe
 
 From the other hand, the equality check `==` for `undefined` and `null` works by the rule, without any conversions. They equal each other and don't equal anything else. That's why (2) `null == 0` is false.
 
-### An uncomparable undefined
+### An incomparable undefined
 
 The value `undefined` shouldn't participate in comparisons at all: