diff --git a/DS/C/Lab/Week3/DecBaseCon.c b/DS/C/Lab/Week3/DecBaseCon.c
new file mode 100644
index 0000000..63a33a7
--- /dev/null
+++ b/DS/C/Lab/Week3/DecBaseCon.c
@@ -0,0 +1,52 @@
+#include <stdio.h>
+#define MAX_SIZE 100
+
+int top = -1;
+char stack[MAX_SIZE];
+
+void push(char c) {
+    if (top < MAX_SIZE - 1) {
+        stack[++top] = c;
+    }
+}
+
+char pop() {
+    if (top >= 0) {
+        return stack[top--];
+    }
+    return '\0';
+}
+
+void decimal_to_base(int decimal, int base) {
+    char digits[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+
+    while (decimal > 0) {
+        push(digits[decimal % base]);
+        decimal /= base;
+    }
+
+    printf("Converted number: ");
+    while (top >= 0) {
+        printf("%c", pop());
+    }
+    printf("\n");
+}
+
+int main() {
+    int decimal, base;
+
+    printf("Enter a decimal number: ");
+    scanf("%d", &decimal);
+
+    printf("Enter the base to convert to (2-36): ");
+    scanf("%d", &base);
+
+    if (base < 2 || base > 36) {
+        printf("Invalid base. Please enter a base between 2 and 36.\n");
+        return 1;
+    }
+
+    decimal_to_base(decimal, base);
+
+    return 0;
+}
diff --git a/DS/C/Lab/Week3/MulSta.c b/DS/C/Lab/Week3/MulSta.c
new file mode 100644
index 0000000..3e14b18
--- /dev/null
+++ b/DS/C/Lab/Week3/MulSta.c
@@ -0,0 +1,45 @@
+#include <stdio.h>
+#define MAX_SIZE 100
+#define NUM_STACKS 3
+
+int tops[NUM_STACKS] = {-1, -1, -1};
+int stack[MAX_SIZE];
+int stack_size = MAX_SIZE / NUM_STACKS;
+
+void push(int stack_num, int value) {
+    int index = stack_num * stack_size + tops[stack_num] + 1;
+    if (tops[stack_num] < stack_size - 1) {
+        tops[stack_num]++;
+        stack[index] = value;
+        printf("Pushed %d to stack %d\n", value, stack_num);
+    } else {
+        printf("Stack %d is full\n", stack_num);
+    }
+}
+
+int pop(int stack_num) {
+    int index = stack_num * stack_size + tops[stack_num];
+    if (tops[stack_num] >= 0) {
+        int value = stack[index];
+        tops[stack_num]--;
+        printf("Popped %d from stack %d\n", value, stack_num);
+        return value;
+    } else {
+        printf("Stack %d is empty\n", stack_num);
+        return -1;
+    }
+}
+
+int main() {
+    push(0, 10);
+    push(0, 20);
+    push(1, 30);
+    push(2, 40);
+
+    pop(0);
+    pop(1);
+    pop(2);
+    pop(2);
+
+    return 0;
+}
diff --git a/DS/C/Lab/Week3/Parenthesis.c b/DS/C/Lab/Week3/Parenthesis.c
new file mode 100644
index 0000000..fa2880b
--- /dev/null
+++ b/DS/C/Lab/Week3/Parenthesis.c
@@ -0,0 +1,51 @@
+#include <stdio.h>
+#define MAX_SIZE 100
+
+char stack[MAX_SIZE];
+int top = -1;
+
+void push(char c) {
+    if (top < MAX_SIZE - 1) {
+        stack[++top] = c;
+    }
+}
+
+char pop() {
+    if (top >= 0) {
+        return stack[top--];
+    }
+    return '\0';
+}
+
+int is_matching_pair(char opening, char closing) {
+    return (opening == '(' && closing == ')') ||
+           (opening == '[' && closing == ']') ||
+           (opening == '{' && closing == '}');
+}
+
+int are_parentheses_balanced(char expr[]) {
+    int i;
+    for (i = 0; expr[i] != '\0'; i++) {
+        if (expr[i] == '(' || expr[i] == '[' || expr[i] == '{') {
+            push(expr[i]);
+        } else if (expr[i] == ')' || expr[i] == ']' || expr[i] == '}') {
+            if (top == -1 || !is_matching_pair(pop(), expr[i])) {
+                return 0;
+            }
+        }
+    }
+    return (top == -1);
+
+int main() {
+    char expr[MAX_SIZE];
+    printf("Enter an expression: ");
+    scanf("%s", expr);
+
+    if (are_parentheses_balanced(expr)) {
+        printf("Parentheses are balanced\n");
+    } else {
+        printf("Parentheses are not balanced\n");
+    }
+
+    return 0;
+}
diff --git a/DS/C/Lab/Week3/StackPalindrome.c b/DS/C/Lab/Week3/StackPalindrome.c
new file mode 100644
index 0000000..7ec7007
--- /dev/null
+++ b/DS/C/Lab/Week3/StackPalindrome.c
@@ -0,0 +1,46 @@
+#include <stdio.h>
+#define MAX_SIZE 100
+
+int top = -1;
+char stack[MAX_SIZE];
+
+void push(char c) {
+    if (top < MAX_SIZE - 1) {
+        stack[++top] = c;
+    }
+}
+
+char pop() {
+    if (top >= 0) {
+        return stack[top--];
+    }
+    return '\0';
+}
+
+int is_palindrome(char *str) {
+    int i;
+    for (i = 0; str[i] != '\0'; i++) {
+        push(str[i]);
+    }
+
+    for (i = 0; str[i] != '\0'; i++) {
+        if (str[i] != pop()) {
+            return 0;
+        }
+    }
+    return 1;
+}
+
+int main() {
+    char str[MAX_SIZE];
+    printf("Enter a string: ");
+    scanf("%s", str);
+
+    if (is_palindrome(str)) {
+        printf("%s is a palindrome.\n", str);
+    } else {
+        printf("%s is not a palindrome.\n", str);
+    }
+
+    return 0;
+}