\[\boxed{\mathbf{422}.}\]
\[\frac{1}{31} + \frac{1}{32} + \frac{1}{33} + \ldots + \frac{1}{39} + \frac{1}{40} > \frac{1}{4}\]
\[\frac{1}{4} = \frac{10}{40};\]
\[\frac{10}{40} = \frac{1}{40} + \frac{1}{40} + \frac{1}{40} + \ldots + \frac{1}{40};\]
\[\frac{1}{31} > \frac{1}{40};\ \frac{1}{32} > \frac{1}{40};\]
\[\ \frac{1}{33} > \frac{1}{40};\ldots;\ \frac{1}{40} = \frac{1}{40}.\]
\[\frac{1}{31} + \frac{1}{32} + \frac{1}{33} + \ldots + \frac{1}{39} + \frac{1}{40} > \frac{10}{40}\]
\[\frac{1}{31} + \frac{1}{32} + \frac{1}{33} + \ldots + \frac{1}{39} + \frac{1}{40} > \frac{1}{4}.\]
\[Что\ и\ требовалось\ доказать.\]