what is ca+ electon config beginning with closest noble gas?

im really not sure

Ca   is normally    1 s²    2s² 2p⁶   3s² 3p⁶   4s²       for 20 electrons

Argon   AR has 18 electrons  

            so   Ca could be    [Ar] 4s²          now remove one electron   to get Ca⁺  =     [ Ar] 4s¹