How many single pole breakers can I put in my 200amp panel?the bottom of my panel has split bus fin on the last couple spots are they:confused: for double pole only? Thank :confused:

No, the slotted busses are not for two-pole breakers. They are for tandem (skinny, twin, etc.) breakers.
Where ever the buss is split like that you can use a tandem breaker for more circuits.

42 overcurrent protection devices are the max allowed by code but it's likely that the panel in your home has a manufacturer defined limit less than that. The manufacturer limit takes precedence.