l = list( a = c('1', '2', '3'), b = c('4', '5', '6'), m = matrix ( c(100, 101, 102, 103, 104, 105, 106, 107), ncol = 2, byrow = TRUE ) ) options(width=300) ul = unlist(l) ul # a1 a2 a3 b1 b2 b3 m1 m2 m3 m4 m5 m6 m7 m8 # "1" "2" "3" "4" "5" "6" "100" "102" "104" "106" "101" "103" "105" "107" typeof(ul) # [1] "character" sum(as.numeric(ul)) # [1] 849