Until [[Windows 95]], it uses an [[IEEE 754-1985]] [[double-precision floating-point]], and the highest representable number by the calculator is 2<sup>1024</sup>, which is slightly above 10<sup>308</sup> (≈1.80 × 10<sup>308</sup>).
In [[Windows 98]] and later, it uses an [[arbitrary-precision arithmetic]] library, replacing the standard [[IEEE]] [[floating point]] library.<ref>{{Cite web |url=httphttps://blogsdevblogs.msdnmicrosoft.com/oldnewthing/archive/2004/05/25/141253.aspx20040525-00 |title=The Old New Thing Blog: When you change the insides, nobody notices |access-date=2007-05-28 |archive-url=https://web.archive.org/web/20100306165045/http://blogs.msdn.com/oldnewthing/archive/2004/05/25/141253.aspx |archive-date=2010-03-06 |url-status=deadlive }}</ref> It offers [[bignum]] precision for basic operations (addition, subtraction, multiplication, division) and 32 digits of precision for advanced operations ([[square root]], [[transcendental function]]s). The largest value that can be represented on the Windows Calculator is currently {{nowrap|<10<sup>10,000</sup>}} and the smallest is {{nowrap|10<sup>−9,999</sup>}}. (Also [[Factorial|!]] calculates the [[gamma function]] which is defined over all real numbers, only excluding the negative integers).
