What is the value of a 1966 100 dollar us note?

In circulated condition, this bill is worth $125.-$200. if there's no letter next to the date, and $200.-$275. if there is a small "A".

I've seen 1966 $100 U.S. notes go for around $300 in uncirculated condition. If it's a 1966-A, the value could be much higher, so an uncirculated bill should be appraised professionally.

Serial NumbersThe serial number is not generally important unless it's low (i.e. lots of leading zeros) or has some special pattern such as a so-called "radar" note; e.g. 12344321.