12 UV leds arduino

Hello all !!!!
How can i get 12 UV leds running on 5v arduino ?????

12-LED UV Flashlight Silver (3xAAA)

What resitor do i need for serial conection????

thank you for the help...

Measure the voltage across an LED when the flashlight is lit. Call that V.

Disconnect one of the LED leads and measure the current through that diode when the flashlight is lit. Call that C.

Subtract V from 5 to get the voltage across the dropping resistor. Divide that voltage by the current C (in Amps) to get Ohms. Use one resistor per diode.

And be very careful with UV LEDs, I was temporarily blinded for a couple of hours by them without even looking into them on purpose !

Thank you guys for the replay!!!

i already desolder the leds from the tourch.
I m going to try to hook up them all.
Thanks for the tip!!!

Thanks for the warning!!!