按百分比计算占比，遇到无限小数都是怎么处理的？

In [1]: total = 11

In [2]: a, b, c = 3, 3, 5

In [3]: list(map(lambda x: x / total, [a, b, c]))
Out[3]: [0.2727272727272727, 0.2727272727272727, 0.45454545454545453]

In [4]: sum(map(lambda x: Decimal(x / total), [a, b, c]))
Out[4]: Decimal('0.9999999999999999444888487687')