diff --git a/sources/operation/ft_classic_op.c b/sources/operation/ft_classic_op.c
new file mode 100644
index 00000000..e12ade5b
--- /dev/null
+++ b/sources/operation/ft_classic_op.c
@@ -0,0 +1,62 @@
+/* ************************************************************************** */
+/*                                                                            */
+/*                                                        :::      ::::::::   */
+/*   ft_classic_op.c                                    :+:      :+:    :+:   */
+/*                                                    +:+ +:+         +:+     */
+/*   By: rparodi <rparodi@student.42.fr>            +#+  +:+       +#+        */
+/*                                                +#+#+#+#+#+   +#+           */
+/*   Created: 2024/05/30 15:33:53 by rparodi           #+#    #+#             */
+/*   Updated: 2024/05/30 16:07:58 by rparodi          ###   ########.fr       */
+/*                                                                            */
+/* ************************************************************************** */
+
+#include "operation.h"
+
+t_error	ft_add(t_i32 first, t_i32 second, t_i64 *result)
+{
+	(*result) = first + second;
+	if ((*result) - first != second)
+		return (ERROR);
+	else
+		return (NO_ERROR);
+}
+
+t_error	ft_subtract(t_i32 first, t_i32 second, t_i64 *result)
+{
+	(*result) = first - second;
+	if ((*result) + first != second)
+		return (ERROR);
+	else
+		return (NO_ERROR);
+}
+
+t_error	ft_multiply(t_i32 first, t_i32 second, t_i64 *result)
+{
+	if (first == 0 || second == 0)
+		return (0);
+	(*result) = first * second;
+	if ((*result) / first != second)
+		return (ERROR);
+	else
+		return (NO_ERROR);
+}
+
+t_error	ft_divide(t_i32 first, t_i32 second, t_i64 *result)
+{
+	if (second == 0)
+		return (ERROR);
+	(*result) = first / second;
+	if ((*result) * first != second)
+		return (ERROR);
+	else
+		return (NO_ERROR);
+}
+
+t_error ft_modulo(t_i32 first, t_i32 second, t_i64 *result)
+{
+    if (second == 0) {
+        return (ERROR);
+    }
+    *result = first % second;
+    return (NO_ERROR);
+}
diff --git a/sources/operation/ft_hard_op.c b/sources/operation/ft_hard_op.c
new file mode 100644
index 00000000..f757a8e0
--- /dev/null
+++ b/sources/operation/ft_hard_op.c
@@ -0,0 +1,54 @@
+/* ************************************************************************** */
+/*                                                                            */
+/*                                                        :::      ::::::::   */
+/*   ft_hard_op.c                                       :+:      :+:    :+:   */
+/*                                                    +:+ +:+         +:+     */
+/*   By: rparodi <rparodi@student.42.fr>            +#+  +:+       +#+        */
+/*                                                +#+#+#+#+#+   +#+           */
+/*   Created: 2024/05/30 15:51:55 by rparodi           #+#    #+#             */
+/*   Updated: 2024/05/30 16:04:33 by rparodi          ###   ########.fr       */
+/*                                                                            */
+/* ************************************************************************** */
+
+#include "operation.h"
+t_error ft_power(t_i32 base, t_i32 exponent, t_i64 *result)
+{
+    t_i32 i;
+	t_i64 tmp;
+
+	i = 0;
+	tmp = base;
+	if (exponent < 0)
+        return (ERROR);
+    while (i < exponent)
+	{
+        (*result) *= base;
+        if ((*result) / base != tmp)
+            return (ERROR);
+		tmp = (*result);
+		i++;
+    }
+    return (NO_ERROR);
+}
+
+t_error ft_decrimented(t_i64 *value)
+{
+	t_i64 tmp;
+
+	tmp = *value;
+	(*value)--;
+	if ((*value) + 1 != tmp)
+		return (ERROR);
+	return (NO_ERROR);
+}
+
+t_error ft_incrimented(t_i64 *value)
+{
+	t_i64 tmp;
+
+	tmp = *value;
+	(*value)++;
+	if ((*value) - 1 != tmp)
+		return (ERROR);
+	return (NO_ERROR);
+}
diff --git a/sources/operation/operation.h b/sources/operation/operation.h
new file mode 100644
index 00000000..7ead4484
--- /dev/null
+++ b/sources/operation/operation.h
@@ -0,0 +1,29 @@
+/* ************************************************************************** */
+/*                                                                            */
+/*                                                        :::      ::::::::   */
+/*   operation.h                                        :+:      :+:    :+:   */
+/*                                                    +:+ +:+         +:+     */
+/*   By: rparodi <rparodi@student.42.fr>            +#+  +:+       +#+        */
+/*                                                +#+#+#+#+#+   +#+           */
+/*   Created: 2024/05/30 16:03:29 by rparodi           #+#    #+#             */
+/*   Updated: 2024/05/30 16:05:30 by rparodi          ###   ########.fr       */
+/*                                                                            */
+/* ************************************************************************** */
+
+#ifndef OPERATION_H
+# define OPERATION_H
+
+# include "minishell.h"
+# include "me/types.h"
+
+t_error	ft_add(t_i32 first, t_i32 second, t_i64 *result);
+t_error	ft_subtract(t_i32 first, t_i32 second, t_i64 *result);
+t_error	ft_multiply(t_i32 first, t_i32 second, t_i64 *result);
+t_error	ft_divide(t_i32 first, t_i32 second, t_i64 *result);
+t_error ft_modulo(t_i32 first, t_i32 second, t_i64 *result);
+t_error ft_power(t_i32 base, t_i32 exponent, t_i64 *result);
+t_error ft_incrimented(t_i64 *value);
+t_error ft_decrimented(t_i64 *value);
+
+#endif
+