Google is hot.
It has a great built-in calculator. You type in the search line "1 pudding in pudding"; it gives "1 pudding = 38 pudding". This I remember from my childhood, but here is what "1 (elephant per square) = 0,000625 hectares", "permanent Planck = 2.6504272 × 10-35 (udav^2) (kg / s)", and "1 (elephant per cubic) = 98.2782929 barrels of oil" for me was a discovery.