The names of the Straw Hats' devil fruits all correspond to Japanese numbers.
Luffy's fruit = Gomu = 5,6
Chopper's fruit = Hito = 1,10
Robin's fruit = Hana = 8,7
Brook's fruit = Yomi = 4,3
The missing numbers are 2 and 9. Kuma's fruit is the one that fits best. Kinemon's also passes iirc.
Now, this is where we'll seriously dive into Oda's autism.
56+110+87+43+29=325.
3 = San
2 = Ni
5 = Go
San Ni Go. Sunny Go.
This was all pointed out in SBS and got a sweating response from Oda.
Yamato is disqualified from joining the crew because there is no way to read Inu as 2 9. Her fruit does not fit into the Sunny Go Equation.