Scratch

You could quite easliy.

First make two variables, any names will do. For the example I'll call one "#" and one "total".

Then you want to set up a simple script like this:

<set{ # }to( 1 )
<repeat( length of list )
<change{ total }by( number { # } of list
<change{ # }by( 1 )
<end>

(Sorry if it's a bit hard to understand > The scratch team haven't updated the blocks to include lists yet.)

This is simply saying, set the # variable to 1 and then change the total variable by the number on the variable # of the list and then changing the # variable by 1.

I hope that helps 

I've added the ability to sum all the #s of a list to my project with a LOT of math functions