Humble Pi: When Math Goes Wrong in the Real World

by Matt Parker

Another limitation of spreadsheets as databases is that they eventually run out. Much like computers having trouble keeping track of time in a 32-digit binary number, Excel has difficulty keeping track of how many rows are in a spreadsheet. In 2010 WikiLeaks presented The Guardian and The New York Times with 92,000 leaked field reports from the war in Afghanistan. Julian Assange delivered them in person to the Guardian offices in London. The journalists quickly confirmed that they seemed to be real but, to their surprise, the reports ended abruptly in April 2009, although they should have gone through to the end of that year. You guessed it: Excel counted its rows as a 16-bit number, so there was a maximum of 216 = 65,536 rows available. So when the journalists opened the data in Excel, all the data after the first 65,536 entries vanished. New York Times journalist Bill Keller described the secret meeting where this was noticed and how “Assange, slipping naturally into the role of office geek, explained that they had hit the limits of Excel.”