Question: How to automatically sum all of Jims posts in this list?

Answer:

  1. Type =SUMPRODUCT(($A$1:$A$16=C6)*$B$1:$B$16) in cell D6.
  2. C6 is the name you want to sum in the list A1:B16.

The final result!

SUMPRODUCT(array1; array2;array3)
Returns the sum of the products of the corresponding ranges or arrays