Was following a Paul McWhorter video and was hookin up a thing to read out the analog and does a thing when it gets to 1000 or higher.
I was turning a potentiometer and nothing changed execept sometimes jumping to 700ish, 1023 for one line every once in a while. Started trouble shooting, plugged the A0 I was reading from to ground and was still 14. Tried at A1 and got 15, A2 was 16, etc.
There are breadboards with bad contacts and broken jumper wires. This seems to happen more often lately.
Do you have a multimeter ? Can you check if a wire is good ? If you do not use a breadboard but directly put it in the Arduino board, then A0 to GND should give a value of 0 and A0 to 5V should give 1023.
The impedance of the inputs is extremely high. When a input is not connected it might go up and down with a nearby voltage.