[SOLVED] 6 pcs of 4 inch 7-segment LED + UNO

The third jpg shows five LEDs in series for the segments, and one for the digital point.
I'm going to assume you use the RED displays, where the LEDs have a Vf of 2 to 2.4volt and a max current of 20mA.

You can safely drop the 220ohm segment resistors to 100ohm if you want more brightness.
That will give (12volt supply - 5*~2.2volt LED) / (100ohm + 15ohm) = ~9mA LED current.

The DP will have the same brightness with a (12volt - 2.2volt LED) / ~0.009A = ~1088ohm = 1k resistor.
Leo..