6v to DC input jack seems to work fine?

Using Arduino General Electronics
15

I may be able to help with your math.

X 6 digits = 60mA.

Really? What about multiplexing?

A typical backlight whether EL or LED will draw 100 mA.

I must have an atypical lcd: its backlighting works fine with a 330ohm resistor to the 3.3v rail.