> However much it cost Microsoft to build Excel. More than that, because you have to replicate a lot of Excel's idiosyncracies in order to get compatibility.

> However much it cost Microsoft to build Excel. More than that, because you have to replicate a lot of Excel's idiosyncracies in order to get compatibility. That's a very challenging task. When Microsoft was putting Lotus 1-2-3 compatibility into Excel back in the late 1980s/early 1990s, this was a much smaller task than replicating Excel would be today. Lotus 1-2-3 was a much less complex product. Most people were upgrading from 1-2-3 v2.x to Excel, which meant that Excel really only had to be compatible with a product that was originally hand-written in x86 assembly.