Here is a useful circuit ... Arduino analog pin is equivalent to the input voltage divided by 11, so 55V ÷ 11 = 5V. In other words, when measuring 55V, the Arduino analog pin will be at its maximum ...

Among all the Arduino boards ... tilde (~) symbol or simply a "PWM" label next to the pin number. If your board has no printed labels, check out its pinout diagram documentation (found on the ...