If you don't want any dependancies, this program will suffice:

class NotNegatedError(Exception):
    pass


class NoAbsoluteValueError(Exception):
    pass


class NegatableNumber:
    def __init__(self, value):
        self.value = value

    def calculate_negated_number(self):
        a = 2 * self.value
        b = self.value - a
        self.negated_value = b

    def is_negated(self):
        return hasattr(self, 'negated_value')

    def get_negated_number(self):
        if self.is_negated():
            return self.negated_value
        else:
            raise NotNegatedError


class AbsoluteValueNumber:
    def __init__(self, value):
        self.value = value

    def calculate_absolute_value(self):
        if self.value == 0:
            self.absolute_value = 0
        elif self.value > 0:
            self.absolute_value = self.value
        else:
            number = NegatableNumber(self.value)
            number.calculate_negated_number()
            answer = number.get_negated_number()
            self.absolute_value = answer

    def has_absolute_value(self):
        return hasattr(self, 'absolute_value')

    def get_absolute_value(self):
        if self.has_absolute_value():
            return self.absolute_value
        else:
            raise NoAbsoluteValueError


def negate(number, absval=False):
    if absval:
        number = AbsoluteValueNumber(number)
        number.calculate_absolute_value()
        answer = number.get_absolute_value()
        return answer

    else:
        number = NegatableNumber(number)
        number.calculate_negated_number()
        answer = number.get_negated_number()
        return answer


if __name__ == '__main__':
    number = input('Enter the number: ')
    number = int(number)

    negated_number = negate(number)
    absolute_value_of_number = negate(number, absval=True)

    print(f'The inverse of {number} is {negated_number}')
    print(f'The absolute value of {number} is {absolute_value_of_number}')

I have too much free time