Assuming a file contains a bunch of numbers, one number per line, like this:

1 2 3 4 5 6 |
1 2 3 4 5 6 |

One can easily calculate the sum and average of all these numbers, by using awk:

1 |
cat numbers | awk '{sum += $1; count += 1} END {print "sum:" sum " avg:" sum/count}' |