diff --git a/04_prompt/prompt.s b/04_prompt/prompt.s
index 2f0cf18..f1c0ca6 100644
--- a/04_prompt/prompt.s
+++ b/04_prompt/prompt.s
@@ -14,6 +14,7 @@
 	greetings_msg:   .asciz "Hi "
 	greetings_size:  .byte .-greetings_msg
 	buffer_size: .byte .-buffer
+	
 	.section .bss
 	buffer: .space 256
 	
diff --git a/05_calc/calc.s b/05_calc/calc.s
new file mode 100644
index 0000000..e497cbb
--- /dev/null
+++ b/05_calc/calc.s
@@ -0,0 +1,45 @@
+# THIS ASSEMBLY FILE CONTAINS THE CALCULATOR'S CODE OF TWO NUMBERS
+
+		.section .rodata
+
+prompt_msg: 	.ascii "Calculator:\n Type [+]: SUM\n Type [-]: SUB\n Type [*]: MUL\n"
+prompt_size:	.byte .-prompt_msg
+
+operand_size:   .data
+		.section .bss
+
+operand:	.space 255
+
+		.section .text
+		.global _start
+
+_start:
+	call prompt
+	call read
+	#call switch_case
+	#call print
+	call exit
+
+read:
+	addi a0, zero, 0
+	la   a1, operand
+	lbu  a2, operand_size
+	addi a7, zero, 63
+	ecall
+	ret
+
+prompt:
+	addi a0, zero, 1
+	la   a1, prompt_msg
+	lbu  a2, prompt_size	
+	addi a7, zero, 64
+	ecall
+	ret
+
+#switch_case:
+
+exit:
+	add  a0, zero, zero
+	addi a7, zero, 93
+	ecall
+	ret