The numprint class provides convenient functions for typesetting numbers. It is possible to customise numerical delimiters (for fractions and thousands...), easily set exponents (simply using sth like 1234.56e78) and properly align numbers in tables. In addition to that the package provides proper spacing between numbers and units in a similar (but less powerful and exhaustive) way as the SIunits package. Ebuild follows...
*** Bug 125449 has been marked as a duplicate of this bug. ***
*** Bug 125450 has been marked as a duplicate of this bug. ***
Created attachment 81672 [details] ebuild for numprint
For the record, numprint has been a part of texlive-latexextra since at least 2012 so it IS available in Portage.
Having just checked, seems that at least in case of texlive-latexextra-2015 the included version of numprint is the same as the latest one available on CTAN (which came out on 2012). In light of the above, there seems to be need for having a separate numprint package. Closing the bug.