Michael Schumacher has taken Nico Rosberg's #3 at Mercedes GP for the coming season.
Rosberg had been listed as #3 on the FIA's entry list before Schumacher came out of retirement, but he will now change to #4.
"Ross [Brawn] knows that I like odd numbers," Schumacher was reported as saying by German newspaper Bild.
A Mercedes GP team spokesperson told Reuters: "Michael has a preference for odd numbers. He asked if he could be the odd number and we were happy to accept."