Looks like you want to format the number to M/K based on its value, I don't think you can simplify it using set analysis as you have to check each aggregated Sum value to decide if you want to write M or K after that.
One approach could be to create island table of units M,K,Unit and allow user to select a unit user would like to see their numbers in , the other field in the same island table is the value in M, K and 1, which will be used to divide the sum expression. This will avoid the if statements but all the numbers will appear in single unit.
