Sub Data_Fill()
Dim lrow As Long
lrow = ActiveSheet.Range("B" & Rows.Count).End(xlUp).Row
Range("AA2:AA" & lrow) = Evaluate("IFERROR(INDEX(A!AA:AA,MATCH(B2,A!B:B,0)),0)+IFERROR(INDEX(B!AA:AA,MATCH(B2,B!B:B,0)),0)+IFERROR(INDEX('C'!AA:AA,MATCH(B2,'C'!B:B,0)),)")
End Sub