driller explained the 4&$A + 5, $t mod 10 makes sense too, right? $ is any value left of the original value. so: if reminder + anyvalue_left or current_value smaller than 3 or greater than 6
the anyvalue_left reverts back to the for loop. the loop goes 16 times (or 15, if left(input,1)=3) if after that, any value is left to be processed => over length of input.
