Connecting nine LEDs in series.. why the results?
In order to decide the current of the led you need to know the max current specs and select a value below that.
In order to calculate a current limiting resistor for a led you need to know the forward voltage drop of the led and the intended current.

When you know all these you use the following equation

$$ R= \frac {V_{in}-V_f}{I_{led}} $$

Where Vin is the supply voltage, Vf is the led forward voltage drop and Iled is the intended led current.  When you connect multiple leds in series then Vf will be the sum of the forward voltage drop of all connected leds.



For your specific example
Vf=2.25V  (for three leds in series 2.25v*3)
Iled=28 mA  

$$ R= \frac {V_{in}-V_f}{I_{led}} = \frac {9V-(2.25V*3)}{0.028A} = 80.36 Ohm $$

If you round the resistor to 82 Ohm

$$ I_{led}= \frac {V_{in}-V_f}{R} = \frac {9V-(2.25V*3)}{82} = 0.027A $$







simulate this circuit &ndash; Schematic created using CircuitLab