def encode_number(number):
    """
    Encodes the number as a symbol. The buckets are:
     (-inf, 0.001, 0.01, 0.1, 1.0, 10.0, 25.0, 50.0, 75.0, 100.0, +inf)
    :param float number: a float number
    :return str: the encoded number
    """
    if number < 0.001:
        return '>number_0001'
    elif number < 0.01:
        return '>number_001'
    elif number < 0.1:
        return '>number_01'
    elif number < 1.0:
        return '>number_1'
    elif number < 10.0:
        return '>number_10'
    elif number < 25.0:
        return '>number_25'
    elif number < 50.0:
        return '>number_50'
    elif number < 75.0:
        return '>number_75'
    elif number < 100.0:
        return '>number_100'
    else:
        return '>number_1000'