avrdude: ser_open(): can't open device

Development Tools IDE 1.x
1

Arduino: 1.8.9 (Windows 10), Board: "Arduino/Genuino Uno"

Sketch uses 1868 bytes (5%) of program storage space. Maximum is 32256 bytes.
Global variables use 188 bytes (9%) of dynamic memory, leaving 1860 bytes for local variables. Maximum is 2048 bytes.
avrdude: ser_open(): can't open device "\.\COM4": The system cannot find the file specified.

Problem uploading to board. See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

2

ak8962726177:
Arduino: 1.8.9 (Windows 10), Board: "Arduino/Genuino Uno"

You have the wrong board selected, you need Tools > Board > Arduino Nano

There are two different bootloaders for the Nano, either Tools > Processor > ATmega328P or Tools > Processor > ATmega328P (Old Bootloader), you will have to try both to see which is correct for your board.

3

This is the second time I've had to split your hijack post off a thread @ak8962726177. This is your final warning. If you do it again, I'm going to give you an account suspension.

4

how to tare the analog reading by use push switch .

/*
ReadAnalogVoltage
Reads an analog input on pin 0, converts it to voltage, and prints the result to the serial monitor.
Attach the center pin of a potentiometer to pin A0, and the outside pins to +5V and ground.

This example code is in the public domain.
*/

// the setup routine runs once when you press reset:
void setup() {
// initialize serial communication at 9600 bits per second:
Serial.begin(9600);
}

// the loop routine runs over and over again forever:
void loop() {
// read the input on analog pin 0:
int sensorValue = analogRead(A0);
// Convert the analog reading (which goes from 0 - 1023) to a voltage (0 - 5V):
float voltage = sensorValue * (5.0 / 1023.0);
// print out the value you read:
Serial.println(voltage);
}