Subnormal number

Summary

A subnormal number, also called a denormal number, is a nonzero floating-point number smaller in absolute value than the smallest normalized floating-point number. It has the minimal exponent and a leading significand digit $0$, so it has fewer significant digits. Subnormal numbers fill the gap between $0$ and the smallest normalized number with evenly spaced values. This gradual underflow ensures that $x - y = 0$ in floating-point arithmetic only when $x = y$.