Man pages matching name math::base::convert::calcpp in section 3pm:

Math::Base::Convert::CalcPP.3pm.en	debian 10 / libmath-base-convert-perl
Math::Base::Convert::CalcPP.3pm.en	debian 11 / libmath-base-convert-perl
Math::Base::Convert::CalcPP.3pm.en	debian 12 / libmath-base-convert-perl