&gt; A unum has three additional fields that make the number self-descriptive: The &quot;ubit&quot; that marks whether a number is exact or in between exact values, the size of the exponent in bits, and the size of the fraction in bits. So not only does the binary point float, the number of significant digits also floats. There is something called &quot;significance arithmetic&quot; that does a crude version of what the unum representation does, but unum math overcomes some serious drawbacks of both significance arithmetic and interval arithmetic.<p>These &quot;unums&quot; have been posted before, e.g. <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=11410349" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=11410349</a>