Decimal Fraction

    a = 0.1 + 0.1 + 0.1
    print(a)
    # get: 0.30000000000000004

    print(a == 0.3)
    # get: False

    print(round(a, 10) == 0.3)
    # get: True

    import decimal

    d = decimal.Decimal 

    print(d(1))
    # get: Decimal('1')
    print(d(0.1))
    # get: Decimal('0.10000000000000000555111512312578270211815834...')
    print(d('0.1'))
    # get: Decimal('0.1')

    print(d('0.1') + d('0.1') + d('0.1') == d('0.3'))
    # get: True

    r = d('1.23456789012345678901234567890')
    print(r)
    # get: Decimal('1.23456789012345678901234567890') (30 places)
    print(r+1)
    # get: Decimal('2.234567890123456789012345679') (28 places)

    decimal.getcontext().prec = 50

    n = d('1.234567890123456789012345678901234567890')
    print(n+1)
    # get: Decimal('2.234567890123456789012345678901234567890') (40 places)

    print(d(6) / d(9))
    # get: Decimal('0.6666666666666666666666666667')

    decimal.getcontext().rounding = 'ROUND_DOWN'

    print(d(6) / d(9))
    # get: Decimal('0.6666666666666666666666666666')

    import fractions

    f = fractions.Fraction

    print(f(1, 10))
    # get: Fraction(1, 10)
    print(f('0.1'))
    # get: Fraction(1, 10)
    print(f('1/10'))
    # get: Fraction(1, 10)
    print(f('1/10') + f('1/10') + f('1/10') == f('3/10'))
    # get: True

    print(f(f(4, 7), f(3, 5)))
    # get: Fraction(20, 21)