diff --git a/code_study/Baekjoon/c/11005.c b/code_study/Baekjoon/c/11005.c
new file mode 100644
index 0000000..2c0c4aa
--- /dev/null
+++ b/code_study/Baekjoon/c/11005.c
@@ -0,0 +1,27 @@
+#include <stdio.h>
+
+int main(){
+    int B, val, i=0;
+    long int N;
+    char res[31];
+
+    scanf("%ld %d", &N, &B);
+
+    while(N!=0){
+        val = N%B;
+        N/=B;
+        if(val>9){
+            res[i]='A'+val-10;
+        }
+        else{
+            res[i]='0'+val;
+        }
+        i++;
+    }
+
+    while(i--){
+        printf("%c",res[i]);
+    }
+
+    return 0;
+}
\ No newline at end of file
diff --git a/code_study/Baekjoon/c/2745.c b/code_study/Baekjoon/c/2745.c
new file mode 100644
index 0000000..781d713
--- /dev/null
+++ b/code_study/Baekjoon/c/2745.c
@@ -0,0 +1,25 @@
+#include <stdio.h>
+
+int main(){
+    char N[31];
+    int B, val, i=0;
+    long int res=0;
+
+    scanf("%s %d",N, &B);
+
+    while(N[i]!='\0'){
+        if(N[i]>='0' && N[i]<='9'){
+            val = N[i] - '0';
+        }
+        else if(N[i]>='A' && N[i]<='Z'){
+            val = N[i] - 'A' + 10;
+        }
+
+        res = res*B+val;
+        i++;
+    }
+
+    printf("%ld", res);
+
+    return 0;
+}
\ No newline at end of file