Famous last words: Lightning can’t hit us at this dist…
Verizon: Really Bad at MathSo I’m investigating leaving Sprint after the news of the previous entry, and this doesn’t inspire confidence in the brand for Verizon.
One would think to place basic computational arithmetic well within the realm of web monkeys that can make a web store for a multi-billion-dollar communications giant. One would also, apparently, be quite wrong. Exactly how do you pay someone 10^-14^th of a penny? 
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Quotes
“I believe in getting into hot water; it keeps you clean.” – G. K. Chesterton
Well, it’s actually a 10^-12^th of a penny. That might be easier. Ask your favourite bank to consider issuing micropayment banknotes.
I’m not the guy in the Digg story. Please read.
Typical mistake – they are representing the prices with IEEE 754 doubles (base-2 floating point numbers with 52 bits of mantissa). The good news is that it’s probably limited to their web form. Their real billing system probably does things correctly.
The details: Just as numbers like 1/3rd can’t be represented in base-10 without infinitely repeating numbers, 0.1 can’t be represented in base-2. They’ve only allocated a finite number of digits to represent the number, so at some point they have to round. That point is at 52 bits, or about 10^-15th of the whole. The proper way to represent dollar amounts is fixed-precision base-10 numbers, but…well, sadly, many don’t. Very few people actually understand floating point numbers, and most people aren’t even aware that they don’t understand them.