diff --git a/modules/01_fundamentals/src/operators.cpp b/modules/01_fundamentals/src/operators.cpp
index 7eb6855..cc7c894 100644
--- a/modules/01_fundamentals/src/operators.cpp
+++ b/modules/01_fundamentals/src/operators.cpp
@@ -2,39 +2,29 @@
 
 namespace fundamentals {
 
-auto absolute_difference(int lhs, int rhs) -> int {
-    // TODO: Return |lhs - rhs| without using std::abs.
-    (void)lhs;
-    (void)rhs;
-    return 0;
+auto absolute_difference(const int lhs, const int rhs) -> int {
+    // NOTE: std::abs not allowed
+    return lhs < rhs ? rhs - lhs : lhs - rhs;
 }
 
-auto is_in_range(int value, int min, int max) -> bool {
-    // TODO: Return true when min <= value <= max (inclusive).
-    (void)value;
-    (void)min;
-    (void)max;
-    return false;
+auto is_in_range(const int value, const int min, const int max) -> bool {
+    return value >= min && value <= max;
 }
 
-auto count_set_bits(std::uint8_t value) -> int {
-    // TODO: Count how many bits are set to 1.
-    (void)value;
-    return 0;
+auto count_set_bits(const std::uint8_t value) -> int {
+    auto count = 0;
+    for (int i = 0; i < 8; i++) {
+        if (((value >> i) & 1) == 1) count++;
+    }
+    return count;
 }
 
-auto logical_and(bool lhs, bool rhs) -> bool {
-    // TODO: Implement logical AND without using &&.
-    (void)lhs;
-    (void)rhs;
-    return false;
+auto logical_and(const bool lhs, const bool rhs) -> bool {
+    return (lhs & rhs) == 1;
 }
 
-auto logical_or(bool lhs, bool rhs) -> bool {
-    // TODO: Implement logical OR without using ||.
-    (void)lhs;
-    (void)rhs;
-    return false;
+auto logical_or(const bool lhs, const bool rhs) -> bool {
+    return (lhs | rhs) == 1;
 }
 
 }  // namespace fundamentals