diff --git a/exercises/18_iterators/iterators4.rs b/exercises/18_iterators/iterators4.rs
index 79e1692b..d73f662a 100644
--- a/exercises/18_iterators/iterators4.rs
+++ b/exercises/18_iterators/iterators4.rs
@@ -3,18 +3,9 @@
 // Execute `rustlings hint iterators4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 pub fn factorial(num: u64) -> u64 {
-    // Complete this function to return the factorial of num
-    // Do not use:
-    // - return
-    // Try not to use:
-    // - imperative style loops (for, while)
-    // - additional variables
-    // For an extra challenge, don't use:
-    // - recursion
-    // Execute `rustlings hint iterators4` for hints.
+    // (1..=n).fold(1, |acc, x| acc * x)
+    (1..=num).product()
 }
 
 #[cfg(test)]
diff --git a/exercises/18_iterators/iterators5.rs b/exercises/18_iterators/iterators5.rs
index a062ee4c..fef4b4a6 100644
--- a/exercises/18_iterators/iterators5.rs
+++ b/exercises/18_iterators/iterators5.rs
@@ -11,8 +11,6 @@
 // Execute `rustlings hint iterators5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::collections::HashMap;
 
 #[derive(Clone, Copy, PartialEq, Eq)]
@@ -33,9 +31,7 @@ fn count_for(map: &HashMap<String, Progress>, value: Progress) -> usize {
 }
 
 fn count_iterator(map: &HashMap<String, Progress>, value: Progress) -> usize {
-    // map is a hashmap with String keys and Progress values.
-    // map = { "variables1": Complete, "from_str": None, ... }
-    todo!();
+    map.values().filter(|val| val == &&value).count()
 }
 
 fn count_collection_for(collection: &[HashMap<String, Progress>], value: Progress) -> usize {
@@ -51,10 +47,9 @@ fn count_collection_for(collection: &[HashMap<String, Progress>], value: Progres
 }
 
 fn count_collection_iterator(collection: &[HashMap<String, Progress>], value: Progress) -> usize {
-    // collection is a slice of hashmaps.
-    // collection = [{ "variables1": Complete, "from_str": None, ... },
-    //     { "variables2": Complete, ... }, ... ]
-    todo!();
+    collection.iter().enumerate().fold(0, |acc, (_, map)| {
+        acc + map.values().filter(|val| val == &&value).count()
+    })
 }
 
 #[cfg(test)]