Darryl Strawberry had his No. 18 retired by the Mets on Saturday at Citi Field, but it was two other jersey numbers that confused Keith Hernandez during the SNY broadcast — including his own.

During the bottom of the first inning of the Mets’ loss to the Diamondbacks in Queens, two fans were shown in the stands, both wearing Mets jerseys.

One had Hernandez’s No. 17 and the other was wearing Gary Carter’s No. 8.

Hernandez’s broadcast partner, Gary Cohen, noted that both Hernandez and Carter were captains during their tenure with the Mets.

Hernandez then responded, “That’s right. That adds up to 15, doesn’t it? 17 and 8, that’s 15.”

Cohen fixed Hernandez’s math issue by telling him the two jersey numbers instead added up to 25, causing those in the booth to laugh.

“Wow,” Cohen said.

It’s unclear how Hernandez made the miscue and it came during another ugly Mets loss, as they fell to 3-6 on their current homestand, which ends Sunday against Arizona.