Add nullish coalescing to multiple articles, refactor operators, renumber the chapter

1-js/02-first-steps/08-operators/3-primitive-conversions-questions/task.md

@@ -0,0 +1,27 @@
+importance: 5
+
+---
+
+# Type conversions
+
+What are results of these expressions?
+
+```js no-beautify
+"" + 1 + 0
+"" - 1 + 0
+true + false
+6 / "3"
+"2" * "3"
+4 + 5 + "px"
+"$" + 4 + 5
+"4" - 2
+"4px" - 2
+7 / 0
+"  -9  " + 5
+"  -9  " - 5
+null + 1
+undefined + 1
+" \t \n" - 2
+```
+
+Think well, write down and then compare with the answer.