awk: numerical addition and grouping

The following script performs a count of the numerical data in a column ($3) and then groups that data by $1.

awk -F'#' 'BEGIN {}
{
sum[$1] += $3
} END {
for ( i in sum ) print i" : "sum[i]
}' $1

Notice how I'm making the value of the array sum[$1] the addition of the numerical values found at field three ($3):

sum[$1] += $3

Essentially evertime awk comes across a $1 value it adds the value of $3 to the array index of $1.