This is a maths prototype model with takes in values from the user and uses it to calculate mean.
This project can be used for tons of different purposes such as calculating average marks, mean of physical quantities.
The need to calculate mean can be different for different people. This makes the project open to everyone.

Step 1: Mathematic Principle Involve

M = sum of the terms / number of terms

Step 2: Description

Materials Required

Arduino Uno
LCD display (16*2)
Keypad matrix (4*4)
Buzzer
Bread board
Jumper wire

Construction

Connect the lcd display to digital pin of Arduino( Rs = 2, En = 3, D4 = 4, D5= 5, D6 = 6,D7 = 7).
Keypad's first 4 pins are row pins then column.
Connect keypad matrix pin to Arduino pin (1 = 12, 2 = 11, 3 = 10, 4 = 9, 5 = A0, 6 = A1, 7 = A2, 8 = A3)
Connect buzzer to digital pin 13 of Arduino.
Open Arduino idle and write the code.

Working

When the user presses a botton on keypad the change in voltage is noted by the MCU. Then it checks for the character assigned to it.
In this project we are using lcd display at 4 bit mode. The value entered by the user will be displayed on the lcd.
The buzzer connected to pin 13 of Arduino will buzz every time you press a button.
All the functions being performed are coded in the MCU. This includes the functionality to calculate mean.

Reference

While I was working on a project based on parralex method. I felt the need to bult a device that could calculate mean of large numbers in seconds.

Step 3: Code

#include <Keypad.h>const byte ROWS = 4; /* four rows */const byte COLS = 4; /* four columns *//* define the symbols on the buttons of the keypads */char hexaKeys[ROWS][COLS] = {  {'1','2','3','A'},  {'4','5','6','B'},  {'7','8','9','C'},  {'*','0','#','D'}};byte rowPins[ROWS] = {12, 11, 10, 9}; /* connect to the row pinouts of the keypad */byte colPins[COLS] = {A0, A1, A2, A3}; Keypad customKeypad = Keypad( makeKeymap(hexaKeys), rowPins, colPins, ROWS, COLS);#include <LiquidCrystal.h>LiquidCrystal lcd(2, 3, 4, 5, 6, 7);int beep = 13;String name;long int a = 0;int count = 1;long int arr[0];long int x = 0;double x_0;int i = 0;long int arr_mean[0];long int y = 0;long big, small;double divide;void setup() {    pinMode(beep, OUTPUT);    lcd.begin(16, 2);     Serial.begin(9600);  Serial.print("Working !");  lcd.clear();  lcd.setCursor(0,0);  lcd.print("MEAN CALCULATOR");  lcd.setCursor(0,1);  lcd.print("Ishaan 11-F");  digitalWrite(beep,HIGH);  delay(50);  digitalWrite(beep,LOW);  delay(2000);  lcd.clear();      }void loop() {     while(true){    lcd.setCursor(0,0);    lcd.print("Enter a number:");        char customkey = customKeypad.getKey();          if (customkey){      char val = customkey;              if(val != 'A' & val != 'B' & val != 'C' & val != 'D' & val != '*'){        if(val == '#')        {                          long int data = a;                    lcd.clear();                  arr[count] = {data};          x = x + arr[count];                        count += 1;          Serial.println(arr[count-1]);                    digitalWrite(beep,HIGH);          delay(50);          digitalWrite(beep,LOW);                    lcd.setCursor(0,0);          lcd.print("You Entered:- ");          lcd.setCursor(0,1);          lcd.print(data);                    digitalWrite(beep,HIGH);          delay(50);          digitalWrite(beep,LOW);                        delay(1000);          lcd.clear();          a = 0;        }                       else        {          digitalWrite(beep,HIGH);          delay(50);          digitalWrite(beep,LOW);                    a = a * 10;          a += (val- 48);                    lcd.setCursor(0,1);          lcd.print(a);                }      }            if(val == '*')      {                    double divide = count - 1;        double x_0 = x/divide;                lcd.clear();        lcd.setCursor(0,0);        lcd.print("Mean = ");        lcd.print(x_0);        delay(5000);          lcd.clear();             break;                    }    }         }}