diff --git a/src/038-unions-and-narrowing/038-introduction-to-unions.problem.ts b/src/038-unions-and-narrowing/037-introduction-to-unions.problem.ts
similarity index 100%
rename from src/038-unions-and-narrowing/038-introduction-to-unions.problem.ts
rename to src/038-unions-and-narrowing/037-introduction-to-unions.problem.ts
diff --git a/src/038-unions-and-narrowing/038-introduction-to-unions.solution.ts b/src/038-unions-and-narrowing/037-introduction-to-unions.solution.ts
similarity index 100%
rename from src/038-unions-and-narrowing/038-introduction-to-unions.solution.ts
rename to src/038-unions-and-narrowing/037-introduction-to-unions.solution.ts
diff --git a/src/038-unions-and-narrowing/039-literal-types.problem.ts b/src/038-unions-and-narrowing/038-literal-types.problem.ts
similarity index 100%
rename from src/038-unions-and-narrowing/039-literal-types.problem.ts
rename to src/038-unions-and-narrowing/038-literal-types.problem.ts
diff --git a/src/038-unions-and-narrowing/039-literal-types.solution.1.ts b/src/038-unions-and-narrowing/038-literal-types.solution.1.ts
similarity index 100%
rename from src/038-unions-and-narrowing/039-literal-types.solution.1.ts
rename to src/038-unions-and-narrowing/038-literal-types.solution.1.ts
diff --git a/src/038-unions-and-narrowing/039-literal-types.solution.2.ts b/src/038-unions-and-narrowing/038-literal-types.solution.2.ts
similarity index 100%
rename from src/038-unions-and-narrowing/039-literal-types.solution.2.ts
rename to src/038-unions-and-narrowing/038-literal-types.solution.2.ts
diff --git a/src/038-unions-and-narrowing/040-how-big-can-a-union-be.explainer.ts b/src/038-unions-and-narrowing/039-how-big-can-a-union-be.explainer.ts
similarity index 100%
rename from src/038-unions-and-narrowing/040-how-big-can-a-union-be.explainer.ts
rename to src/038-unions-and-narrowing/039-how-big-can-a-union-be.explainer.ts
diff --git a/src/038-unions-and-narrowing/041-literals-vs-wider-types.explainer.ts b/src/038-unions-and-narrowing/040-literals-vs-wider-types.explainer.ts
similarity index 100%
rename from src/038-unions-and-narrowing/041-literals-vs-wider-types.explainer.ts
rename to src/038-unions-and-narrowing/040-literals-vs-wider-types.explainer.ts
diff --git a/src/038-unions-and-narrowing/042-narrowing-unions-with-typeof.explainer.ts b/src/038-unions-and-narrowing/041-narrowing-unions-with-typeof.explainer.ts
similarity index 100%
rename from src/038-unions-and-narrowing/042-narrowing-unions-with-typeof.explainer.ts
rename to src/038-unions-and-narrowing/041-narrowing-unions-with-typeof.explainer.ts
diff --git a/src/038-unions-and-narrowing/043-narrowing-with-if-statements.problem.ts b/src/038-unions-and-narrowing/042-narrowing-with-if-statements.problem.ts
similarity index 100%
rename from src/038-unions-and-narrowing/043-narrowing-with-if-statements.problem.ts
rename to src/038-unions-and-narrowing/042-narrowing-with-if-statements.problem.ts
diff --git a/src/038-unions-and-narrowing/043-narrowing-with-if-statements.solution.1.ts b/src/038-unions-and-narrowing/042-narrowing-with-if-statements.solution.1.ts
similarity index 100%
rename from src/038-unions-and-narrowing/043-narrowing-with-if-statements.solution.1.ts
rename to src/038-unions-and-narrowing/042-narrowing-with-if-statements.solution.1.ts
diff --git a/src/038-unions-and-narrowing/043-narrowing-with-if-statements.solution.2.ts b/src/038-unions-and-narrowing/042-narrowing-with-if-statements.solution.2.ts
similarity index 100%
rename from src/038-unions-and-narrowing/043-narrowing-with-if-statements.solution.2.ts
rename to src/038-unions-and-narrowing/042-narrowing-with-if-statements.solution.2.ts
diff --git a/src/038-unions-and-narrowing/043-narrowing-with-if-statements.solution.3.ts b/src/038-unions-and-narrowing/042-narrowing-with-if-statements.solution.3.ts
similarity index 100%
rename from src/038-unions-and-narrowing/043-narrowing-with-if-statements.solution.3.ts
rename to src/038-unions-and-narrowing/042-narrowing-with-if-statements.solution.3.ts
diff --git a/src/038-unions-and-narrowing/043-narrowing-with-if-statements.solution.4.ts b/src/038-unions-and-narrowing/042-narrowing-with-if-statements.solution.4.ts
similarity index 100%
rename from src/038-unions-and-narrowing/043-narrowing-with-if-statements.solution.4.ts
rename to src/038-unions-and-narrowing/042-narrowing-with-if-statements.solution.4.ts
diff --git a/src/038-unions-and-narrowing/043-narrowing-with-if-statements.solution.5.ts b/src/038-unions-and-narrowing/042-narrowing-with-if-statements.solution.5.ts
similarity index 100%
rename from src/038-unions-and-narrowing/043-narrowing-with-if-statements.solution.5.ts
rename to src/038-unions-and-narrowing/042-narrowing-with-if-statements.solution.5.ts
diff --git a/src/038-unions-and-narrowing/044-narrowing-with-boolean-wont-work.explainer.ts b/src/038-unions-and-narrowing/043-narrowing-with-boolean-wont-work.explainer.ts
similarity index 100%
rename from src/038-unions-and-narrowing/044-narrowing-with-boolean-wont-work.explainer.ts
rename to src/038-unions-and-narrowing/043-narrowing-with-boolean-wont-work.explainer.ts
diff --git a/src/038-unions-and-narrowing/045-throwing-errors-to-narrow.problem.ts b/src/038-unions-and-narrowing/044-throwing-errors-to-narrow.problem.ts
similarity index 100%
rename from src/038-unions-and-narrowing/045-throwing-errors-to-narrow.problem.ts
rename to src/038-unions-and-narrowing/044-throwing-errors-to-narrow.problem.ts
diff --git a/src/038-unions-and-narrowing/045-throwing-errors-to-narrow.solution.ts b/src/038-unions-and-narrowing/044-throwing-errors-to-narrow.solution.ts
similarity index 100%
rename from src/038-unions-and-narrowing/045-throwing-errors-to-narrow.solution.ts
rename to src/038-unions-and-narrowing/044-throwing-errors-to-narrow.solution.ts
diff --git a/src/038-unions-and-narrowing/046-narrowing-with-instanceof-statements.problem.ts b/src/038-unions-and-narrowing/045-narrowing-with-instanceof-statements.problem.ts
similarity index 100%
rename from src/038-unions-and-narrowing/046-narrowing-with-instanceof-statements.problem.ts
rename to src/038-unions-and-narrowing/045-narrowing-with-instanceof-statements.problem.ts
diff --git a/src/038-unions-and-narrowing/046-narrowing-with-instanceof-statements.solution.ts b/src/038-unions-and-narrowing/045-narrowing-with-instanceof-statements.solution.ts
similarity index 100%
rename from src/038-unions-and-narrowing/046-narrowing-with-instanceof-statements.solution.ts
rename to src/038-unions-and-narrowing/045-narrowing-with-instanceof-statements.solution.ts
diff --git a/src/038-unions-and-narrowing/047-narrowing-with-in-statements.problem.ts b/src/038-unions-and-narrowing/046-narrowing-with-in-statements.problem.ts
similarity index 100%
rename from src/038-unions-and-narrowing/047-narrowing-with-in-statements.problem.ts
rename to src/038-unions-and-narrowing/046-narrowing-with-in-statements.problem.ts
diff --git a/src/038-unions-and-narrowing/047-narrowing-with-in-statements.solution.ts b/src/038-unions-and-narrowing/046-narrowing-with-in-statements.solution.ts
similarity index 100%
rename from src/038-unions-and-narrowing/047-narrowing-with-in-statements.solution.ts
rename to src/038-unions-and-narrowing/046-narrowing-with-in-statements.solution.ts
diff --git a/src/038-unions-and-narrowing/048-narrowing-unknown-to-a-value.problem.ts b/src/038-unions-and-narrowing/047-narrowing-unknown-to-a-value.problem.ts
similarity index 100%
rename from src/038-unions-and-narrowing/048-narrowing-unknown-to-a-value.problem.ts
rename to src/038-unions-and-narrowing/047-narrowing-unknown-to-a-value.problem.ts
diff --git a/src/038-unions-and-narrowing/048-narrowing-unknown-to-a-value.solution.ts b/src/038-unions-and-narrowing/047-narrowing-unknown-to-a-value.solution.ts
similarity index 100%
rename from src/038-unions-and-narrowing/048-narrowing-unknown-to-a-value.solution.ts
rename to src/038-unions-and-narrowing/047-narrowing-unknown-to-a-value.solution.ts
diff --git a/src/038-unions-and-narrowing/049-narrowing-with-ternaries.problem.ts b/src/038-unions-and-narrowing/048-narrowing-with-ternaries.problem.ts
similarity index 100%
rename from src/038-unions-and-narrowing/049-narrowing-with-ternaries.problem.ts
rename to src/038-unions-and-narrowing/048-narrowing-with-ternaries.problem.ts
diff --git a/src/038-unions-and-narrowing/049-narrowing-with-ternaries.solution.ts b/src/038-unions-and-narrowing/048-narrowing-with-ternaries.solution.ts
similarity index 100%
rename from src/038-unions-and-narrowing/049-narrowing-with-ternaries.solution.ts
rename to src/038-unions-and-narrowing/048-narrowing-with-ternaries.solution.ts
diff --git a/src/038-unions-and-narrowing/050-narrowing-with-nullish-coalescing.problem.ts b/src/038-unions-and-narrowing/049-narrowing-with-nullish-coalescing.problem.ts
similarity index 100%
rename from src/038-unions-and-narrowing/050-narrowing-with-nullish-coalescing.problem.ts
rename to src/038-unions-and-narrowing/049-narrowing-with-nullish-coalescing.problem.ts
diff --git a/src/038-unions-and-narrowing/050-narrowing-with-nullish-coalescing.solution.ts b/src/038-unions-and-narrowing/049-narrowing-with-nullish-coalescing.solution.ts
similarity index 100%
rename from src/038-unions-and-narrowing/050-narrowing-with-nullish-coalescing.solution.ts
rename to src/038-unions-and-narrowing/049-narrowing-with-nullish-coalescing.solution.ts
diff --git a/src/038-unions-and-narrowing/051-intro-to-discriminated-unions.problem.ts b/src/038-unions-and-narrowing/050-intro-to-discriminated-unions.problem.ts
similarity index 100%
rename from src/038-unions-and-narrowing/051-intro-to-discriminated-unions.problem.ts
rename to src/038-unions-and-narrowing/050-intro-to-discriminated-unions.problem.ts
diff --git a/src/038-unions-and-narrowing/051-intro-to-discriminated-unions.solution.ts b/src/038-unions-and-narrowing/050-intro-to-discriminated-unions.solution.ts
similarity index 100%
rename from src/038-unions-and-narrowing/051-intro-to-discriminated-unions.solution.ts
rename to src/038-unions-and-narrowing/050-intro-to-discriminated-unions.solution.ts
diff --git a/src/038-unions-and-narrowing/052-destructuring-a-discriminated-union.problem.ts b/src/038-unions-and-narrowing/051-destructuring-a-discriminated-union.problem.ts
similarity index 100%
rename from src/038-unions-and-narrowing/052-destructuring-a-discriminated-union.problem.ts
rename to src/038-unions-and-narrowing/051-destructuring-a-discriminated-union.problem.ts
diff --git a/src/038-unions-and-narrowing/052-destructuring-a-discriminated-union.solution.ts b/src/038-unions-and-narrowing/051-destructuring-a-discriminated-union.solution.ts
similarity index 100%
rename from src/038-unions-and-narrowing/052-destructuring-a-discriminated-union.solution.ts
rename to src/038-unions-and-narrowing/051-destructuring-a-discriminated-union.solution.ts
diff --git a/src/038-unions-and-narrowing/053-narrowing-a-discriminated-union-with-a-switch-statement.problem.ts b/src/038-unions-and-narrowing/052-narrowing-a-discriminated-union-with-a-switch-statement.problem.ts
similarity index 100%
rename from src/038-unions-and-narrowing/053-narrowing-a-discriminated-union-with-a-switch-statement.problem.ts
rename to src/038-unions-and-narrowing/052-narrowing-a-discriminated-union-with-a-switch-statement.problem.ts
diff --git a/src/038-unions-and-narrowing/053-narrowing-a-discriminated-union-with-a-switch-statement.solution.ts b/src/038-unions-and-narrowing/052-narrowing-a-discriminated-union-with-a-switch-statement.solution.ts
similarity index 100%
rename from src/038-unions-and-narrowing/053-narrowing-a-discriminated-union-with-a-switch-statement.solution.ts
rename to src/038-unions-and-narrowing/052-narrowing-a-discriminated-union-with-a-switch-statement.solution.ts
diff --git a/src/038-unions-and-narrowing/054-narrowing-with-switch-true.explainer.ts b/src/038-unions-and-narrowing/053-narrowing-with-switch-true.explainer.ts
similarity index 100%
rename from src/038-unions-and-narrowing/054-narrowing-with-switch-true.explainer.ts
rename to src/038-unions-and-narrowing/053-narrowing-with-switch-true.explainer.ts
diff --git a/src/038-unions-and-narrowing/055-destructuring-a-discriminated-tuple.problem.ts b/src/038-unions-and-narrowing/054-destructuring-a-discriminated-tuple.problem.ts
similarity index 100%
rename from src/038-unions-and-narrowing/055-destructuring-a-discriminated-tuple.problem.ts
rename to src/038-unions-and-narrowing/054-destructuring-a-discriminated-tuple.problem.ts
diff --git a/src/038-unions-and-narrowing/055-destructuring-a-discriminated-tuple.solution.ts b/src/038-unions-and-narrowing/054-destructuring-a-discriminated-tuple.solution.ts
similarity index 100%
rename from src/038-unions-and-narrowing/055-destructuring-a-discriminated-tuple.solution.ts
rename to src/038-unions-and-narrowing/054-destructuring-a-discriminated-tuple.solution.ts
diff --git a/src/038-unions-and-narrowing/056-discriminated-booleans.problem.ts b/src/038-unions-and-narrowing/055-discriminated-booleans.problem.ts
similarity index 100%
rename from src/038-unions-and-narrowing/056-discriminated-booleans.problem.ts
rename to src/038-unions-and-narrowing/055-discriminated-booleans.problem.ts
diff --git a/src/038-unions-and-narrowing/056-discriminated-booleans.solution.ts b/src/038-unions-and-narrowing/055-discriminated-booleans.solution.ts
similarity index 100%
rename from src/038-unions-and-narrowing/056-discriminated-booleans.solution.ts
rename to src/038-unions-and-narrowing/055-discriminated-booleans.solution.ts