@ECHO OFF
SETLOCAL ENABLEDELAYEDEXPANSION
SET SUM=0
FOR %%i IN (1 2 3 4 5 6 7 8 9 10) DO (
  SET /A SUM=%SUM% + %%i
)
ECHO %SUM%

SET SUM=0
FOR %%i IN (1 2 3 4 5 6 7 8 9 10) DO (
  SET /A SUM=!SUM! + %%i
)
ECHO %SUM%