The Query Needs to populate Most recent Data and time of the values Captured in those Fields.

Hi Friends, 

Already My Table has Callback1DateTime, Callback2DateTime, Callback3DateTime, Callback4DateTime and Callback5DateTime

I Need to  add ‘Latest Callback’ that’s a calculated field based on Callback1DateTime, Callback2DateTime, Callback3DateTime, Callback4DateTime, Callback5DateTime and Callback6DateTime. I need Latest Callback to be populated with the most recent date and time of the values captured in those fields

Can you please help me T-SQL query about it. 

Many Thanks.