diff --git a/1-exercises/A-undefined/exercise.js b/1-exercises/A-undefined/exercise.js
index 0acfc78d..119b7b26 100644
--- a/1-exercises/A-undefined/exercise.js
+++ b/1-exercises/A-undefined/exercise.js
@@ -12,7 +12,7 @@
 // Example 1
 let a;
 console.log(a);
-
+// a doesnt have a value
 
 // Example 2
 function sayHello() {
@@ -21,7 +21,7 @@ function sayHello() {
 
 let hello = sayHello();
 console.log(hello);
-
+//
 
 // Example 3
 function sayHelloToUser(user) {
@@ -29,8 +29,9 @@ function sayHelloToUser(user) {
 }
 
 sayHelloToUser();
-
+//the user value is undefined in the string
 
 // Example 4
 let arr = [1,2,3];
 console.log(arr[3]);
+// this array doesn't have a fourth value (the first value in the array is designated position 0)
\ No newline at end of file
diff --git a/1-exercises/B-while-loop/exercise.js b/1-exercises/B-while-loop/exercise.js
index b459888f..95ede76b 100644
--- a/1-exercises/B-while-loop/exercise.js
+++ b/1-exercises/B-while-loop/exercise.js
@@ -6,9 +6,16 @@
 */
 
 function evenNumbers(n) {
-    // TODO
+    if (!n) return
+    const evenNums = []
+    let counter = 0;
+    while (evenNums.length < n) {
+      evenNums.push(counter * 2)
+      counter++;
+    }
+    console.log(evenNums.toString())
 }
-
+evenNumbers(1)
 evenNumbers(3); // should output 0,2,4
 evenNumbers(0); // should output nothing
 evenNumbers(10); // should output 0,2,4,6,8,10,12,14,16,18
diff --git a/1-exercises/D-do-while/exercise.js b/1-exercises/D-do-while/exercise.js
index f10d0764..016324d5 100644
--- a/1-exercises/D-do-while/exercise.js
+++ b/1-exercises/D-do-while/exercise.js
@@ -7,7 +7,13 @@
 */
 
 function evenNumbersSum(n) {
-    // TODO
+    let sum = 0
+    let i = 0
+    do {
+        sum += (i * 2); 
+        i++;
+    } while (i < n) 
+    return sum
 }
 
 console.log(evenNumbersSum(3)); // should output 6