A perfect number is a number whose factors ( excluding the number itself as a factor ) add up to the number .
一个完美数字是一个这样的数值，它的因子（数字本身不能作为因子）相加起来等于该数值。
These fees add up to rather large sums .
这些费用累加后的总和相当巨大。
These three things add up pretty significantly .
这三样东西加起来效果相当显著。
All those fannie mae shares do not add up to much money .
然而全部这些房利美股票加起来，也不值多少钱。
Although a change to ajax technology would only make searches milliseconds faster those milliseconds add up allowing people to do more searches faster .