Return second biggest value

[Anonymous]

Hi!

I am looking for a formula that will return the second biggest value. 

Below is the formula that is returning me the biggest value from a certain dataset:

LAstMonth = 
 CALCULATE(
 SUM(Q1_Subledger[Amount incl VAT]), 
 FILTER(Q1_Subledger,Q1_Subledger[Source.Name]=MAX(Q1_Subledger[Source.Name])
 ))

I am looking for something that will return the second biggest value... any idea? Name of the table is Q1_Subledger. So, from below dataset, I would like to have a sum of "Amount incl VAT" for 201903_6120.xlsx. And, when I add a set for 201905_6120.xlsx, I'd like the formula to pick 201904_6120 (so second biggest value).

Source.Name	Amount incl VAT
201901_6120.xlsx	5000
201901_6120.xlsx	654
201901_6120.xlsx	2001
201901_6120.xlsx	225
201901_6120.xlsx	23
201901_6120.xlsx	5564
201901_6120.xlsx	58797
201902_6120.xlsx	46461
201902_6120.xlsx	0
201902_6120.xlsx	45468
201902_6120.xlsx	645461
201902_6120.xlsx	5456874
201902_6120.xlsx	163546
201902_6120.xlsx	500
201903_6120.xlsx	600
201903_6120.xlsx	987
201903_6120.xlsx	415
201903_6120.xlsx	525
201903_6120.xlsx	858
201903_6120.xlsx	747
201903_6120.xlsx	969
201904_6120.xlsx	636
201904_6120.xlsx	302
201904_6120.xlsx	301
201904_6120.xlsx	201
201904_6120.xlsx	502

thank you!

[viniscera]

Guy, you are amazing! I had solved my problem with your code! Thanks!

[Zubair_Muhammad · Accepted solution]

@Anonymous 

Try following measure

SecondLAstMonth =
SUMX (
    TOPN (
        1,
        TOPN ( 2, VALUES ( Q1_Subledger[Source.Name] ), [Source.Name], DESC ),
        [Source.Name], ASC
    ),
    CALCULATE ( SUM ( Q1_Subledger[Amount incl VAT] ) )
)