# Gavin Andresen
# 2011-03-30 17:11:31
# https://bitcointalk.org/index.php?topic=4086.msg75698#msg75698

Can you'all educate me about these mythical rounding errors that require using GMP? @p{par}

I can see, maybe, if you're computing interest down to the penny on a 30-year mortgage you might conceivably be off by a penny if you use 64-bit floats instead of 64-bit integers, although even there you're going to have to think hard about rounding as you get integer remainders. @p{par}

And I can see being really careful if you're writing a bitcoin exchange site or bitcoin bank that deals in thousands of internal transactions that must all balance exactly. @p{par}

But for the typical PHP website that is just going to add up 10 items in a shopping cart using plain-old PHP Numbers will be just fine.   I don't see PayPal recommending that PHP users of it's APIs install GMP.  Recommending that any website dealing with bitcoins compile genjix' fork and use GMP is a really good way to ensure that nobody accepts bitcoins. @p{par}