The following libraries are all about working with numbers.
Boost.Integer provides integral types to, for example, specify the exact number of bytes used by a variable.
Boost.Accumulators provides accumulators that you can pass numbers to when you are calculating values like the mean or standard deviation.
Boost.MinMax lets you get the smallest and largest number in a container with one function call.
Boost.Random provides random number generators.
Boost.NumericConversion provides a cast operator that protects against unintended overflows.