diff --git a/Book/10_Code_Conversion_BCD_Arithmetic_and_16Bit_Data_Operation/Illustrative_Program_10.1.1.asm b/Book/10_Code_Conversion_BCD_Arithmetic_and_16Bit_Data_Operation/Illustrative_Program_10.1.1.asm
index 9262202..d397899 100644
--- a/Book/10_Code_Conversion_BCD_Arithmetic_and_16Bit_Data_Operation/Illustrative_Program_10.1.1.asm
+++ b/Book/10_Code_Conversion_BCD_Arithmetic_and_16Bit_Data_Operation/Illustrative_Program_10.1.1.asm
@@ -33,7 +33,7 @@ BCDBIN: PUSH D       ;Push D to stack
         MOV C, A     ;C = A
 
         MOV A, B     ;A = B
-        ANI 0F0H     ;A and F0H (Mask lower nibble)
+        ANI F0H     ;A and F0H (Mask lower nibble)
         RRC          ;Rotate Right (Withour carry)
         RRC          ;Rotate Right (Withour carry)
         RRC          ;Rotate Right (Withour carry)
@@ -48,4 +48,4 @@ BCDBIN: PUSH D       ;Push D to stack
         
         ADD C        ;A = A + C
         POP D        ;Pop stack and place in D
-        RET          ;Return
\ No newline at end of file
+        RET          ;Return