diff --git a/test1/fibonacci/src/main.c b/test1/fibonacci/src/main.c
new file mode 100644
index 0000000..8d46f26
--- /dev/null
+++ b/test1/fibonacci/src/main.c
@@ -0,0 +1,48 @@
+#include <stdio.h>
+
+int fibonacciDigit(int n);
+
+int main() {
+    printf("%d\n", fibonacciDigit(7));
+    printf("%d\n", fibonacciDigit(11));
+
+    return 0;
+}
+
+int fibonacciDigit(int n) {
+    if (n <= 0)
+        return -1;
+    if (n == 1 || n == 2)
+        return 1;
+
+    int currentPos = 2;
+    long long a = 1, b = 1;
+
+    while (currentPos < n) {
+        long long next = a + b;
+        a = b;
+        b = next;
+
+        long long temp = next;
+        int numDigits = 0;
+        while (temp > 0) {
+            numDigits++;
+            temp /= 10;
+        }
+
+        if (currentPos + numDigits >= n) {
+            int leftSpace = n - currentPos - 1;
+            long long divisor = 1;
+
+            for (int i = 0; i < numDigits - leftSpace - 1; i++) {
+                divisor *= 10;
+            }
+
+            return (int)((next / divisor) % 10);
+        }
+
+        currentPos += numDigits;
+    }
+
+    return -1;
+}
diff --git a/test1/maxSum/src/main.c b/test1/maxSum/src/main.c
new file mode 100644
index 0000000..c2ca0fb
--- /dev/null
+++ b/test1/maxSum/src/main.c
@@ -0,0 +1,50 @@
+#include <stdio.h>
+
+void printMax(int *numbers, const int size);
+
+int binaryDigitSum(int num);
+
+int main() {
+    int numbers[] = {15, 7, 3, 31, 63, 1, 255, 127, 85};
+    const int size = sizeof(numbers) / sizeof(numbers[0]);
+
+    printMax(numbers, size);
+
+    return 0;
+}
+
+void printMax(int *numbers, const int size) {
+    int maxSum = -1;
+    int maxNumbers[size];
+    int count = 0;
+
+    for (int i = 0; i < size; i++) {
+        int currentSum = binaryDigitSum(numbers[i]);
+
+        if (currentSum > maxSum) {
+            maxSum = currentSum;
+            count = 0;
+            maxNumbers[count++] = numbers[i];
+        } else if (currentSum == maxSum)
+            maxNumbers[count++] = numbers[i];
+    }
+
+    for (int i = 0; i < count; i++)
+        printf("%d ", maxNumbers[i]);
+    printf("\n");
+}
+
+int binaryDigitSum(int num) {
+    int sum = 0;
+
+    if (num < 0)
+        num = -num;
+
+    while (num > 0) {
+        sum += num % 2;
+        num = num / 2;
+    }
+
+    return sum;
+}
+
diff --git a/test1/selectionSort/src/main.c b/test1/selectionSort/src/main.c
new file mode 100644
index 0000000..f51c3f7
--- /dev/null
+++ b/test1/selectionSort/src/main.c
@@ -0,0 +1,45 @@
+#include <stdio.h>
+
+void selectionSort(int *arr, int n);
+
+void printArray(int *arr, int n);
+
+int main() {
+    int arr[] = {64, 25, 12, 22, 11};
+    int n = sizeof(arr) / sizeof(arr[0]);
+
+    printf("Initial array: ");
+    printArray(arr, n);
+
+    selectionSort(arr, n);
+
+    printf("Sorted array: ");
+    printArray(arr, n);
+
+    return 0;
+}
+
+void selectionSort(int *arr, int n) {
+    for (int i = 0; i < n - 1; ++i) {
+        int minIndex = i;
+        for (int j = i + 1; j < n; ++j) {
+            if (arr[j] < arr[minIndex]) {
+                minIndex = j;
+            }
+        }
+
+        if (minIndex != i) {
+            int temp = arr[i];
+            arr[i] = arr[minIndex];
+            arr[minIndex] = temp;
+        }
+    }
+}
+
+void printArray(int *arr, int n) {
+    for (int i = 0; i < n; i++) {
+        printf("%d ", arr[i]);
+    }
+    printf("\n");
+}
+