Copy of the vmath.vim plugin by Damian Conway, to do math on a column of numbers
Create mappings, for example
vmap <expr> ++ VMATH_YankAndAnalyse()
nmap ++ vip++
Type a column of numbers, then use the mappings. Once you have computed the sum, it is available in the default yank buffer, and also in the "s buffer. The average is available in the "a buffer, the minimum in the "n buffer, the maximum in the "x buffer and the min-to-max range in the "r buffer.