Determining values of thermistors
Usually with a 3 digit marking, the first two digits are the first two digits of the value (resistance, capacitance, etc), and the third digit is the multiplier (or the number of zeros to follow)  

So for resistance 823 is 82 * 10^3, or 82,000 ohms.  

The rest would be:  

821 = 82 * 10^1 = 820 ohms.
561 = 56 * 10^1 = 560 ohms.
103 = 10 * 10^3 = 10k ohms.
56  = 56 * 10^0 = 56 ohms (often this is marked as 560)    

If you have a multimeter measure them (as W5VO suggests) at around 25 deg C to see if they agree with this.