How do I calculate the total of Year Month and Days as given snapshot.
As per comment try following formulas.
For days =MOD(SUM(D2:D7),30)
For months =MOD(SUM(C2:C7)+INT(SUM(D2:D7)/30),12)
For years =SUM(B2:B7)+INT((INT(SUM(D2:D7)/30)+SUM(C2:C7))/12)