diff --git a/Part3/09_memory/kernel/kernel.c b/Part3/09_memory/kernel/kernel.c
index 2c0a99e..2cc209d 100644
--- a/Part3/09_memory/kernel/kernel.c
+++ b/Part3/09_memory/kernel/kernel.c
@@ -117,15 +117,15 @@
 
 
     int digit_len(unsigned digit) {
-        if (x >= 1000000000) return 10;
-        if (x >= 100000000)  return 9;
-        if (x >= 10000000)   return 8;
-        if (x >= 1000000)    return 7;
-        if (x >= 100000)     return 6;
-        if (x >= 10000)      return 5;
-        if (x >= 1000)       return 4;
-        if (x >= 100)        return 3;
-        if (x >= 10)         return 2;
+        if (digit >= 1000000000) return 10;
+        if (digit >= 100000000)  return 9;
+        if (digit >= 10000000)   return 8;
+        if (digit >= 1000000)    return 7;
+        if (digit >= 100000)     return 6;
+        if (digit >= 10000)      return 5;
+        if (digit >= 1000)       return 4;
+        if (digit >= 100)        return 3;
+        if (digit >= 10)         return 2;
         return 1;
     }