Number Series Codes using C#

Introduction

This article will help you learn and write code on some famous number series. For demonstration purposes, I used Visual Studio Code for the C# code.

To set up the environment for C# in Visual Studio Code, refer here.

Check even or odd number

public void OddEvenNumber()
{
// Number which is divisible by 2 is known as Even number
// Number which is not divisible by 2 is known as Odd number
Console.Write("Enter the number: ");
int number = Convert.ToInt32(Console.ReadLine());
if (number % 2 == 0) // check number after division is zero
{
Console.Write(number + " is Even Number"); // If divisible by number
}
else
{
Console.Write(number + " is Odd number"); // if not divisble by number
}
}

Output

Check Prime Number

public void PrimeNumber()
{
// Prime numbers are numbers divisible by 1 and itself.
Console.Write("Enter the number: ");
int number = Convert.ToInt32(Console.ReadLine());
int i, m = 0, count = 0;
m = number / 2;
for (i = 2; i <= m; i++) // check number is divisible by any another number
{
if (number % i == 0) // If number is divisible by another number
{
count = 1; // reassign the count to 1
break; // break the for loop
}
}
if (number > 1 && count == 0) // number should be greater than 1.
{
Console.Write(number + " is prime number");
}
else
{
Console.Write(number + " is non prime number");
}
}

Output

Print prime number from 1 to 100

public void PrintPrimeNumber1To100()
{
// Prime number are the number which is divisible by 1 or itself.
bool isPrimeNumber = true; // check number is prime number
int outerloop, innerloop; // declare to
Console.WriteLine("Prime Numbers are : ");
for (outerloop = 2; outerloop <= 100; outerloop++)
{
for (innerloop= 2; innerloop <= 100; innerloop++)
{
if (outerloop != innerloop && outerloop % innerloop== 0)
{
isPrimeNumber = false;
break;
}
}
if (isPrimeNumber) // If number is prime number print them on console.
{
Console.Write("\t" + outerloop);
}
isPrimeNumber = true;
}
Console.ReadLine();
}

Output

Print factorial of input number

public void Factorial()
{
// Factorial of number 4 is: 4*3*2*1 = 24
int num, factorial = 1;
Console.Write("Enter the number: ");
num = Convert.ToInt32(Console.ReadLine());
while (num >= 1) // check number is greater or equal to 1
{
factorial = factorial * num; // multiply the number
num--; // decrement the number by 1
}
Console.Write("Factorial: " + factorial);
}

Output

Print the reverse number of input number

public void ReverseNumber()
{
// ReverseNumber
int originalNumber, reverseNumber = 0;
Console.Write("Enter the number: ");
originalNumber = Convert.ToInt32(Console.ReadLine());
while (originalNumber >= 1)
{
reverseNumber = reverseNumber * 10 + originalNumber % 10; // multiply the reverseNumber with 10 and modulus on orginal number
originalNumber = originalNumber / 10;
}
Console.Write("Reverse Number: " + reverseNumber);
}

Output

Check if input number is palidrome or not

public void CheckPalidromeNumber()
{
// Palidrome number is number that remains same when its digit are reversed.
int numb, temp = 0, orginalNumb;
Console.Write("Enter the number: ");
numb = Convert.ToInt32(Console.ReadLine());
orginalNumb = numb; // store the entered number into original number
while (numb >= 1)
{
temp = temp * 10 + numb % 10;
numb = numb / 10;
}
if (temp == orginalNumb) // check orginal number and temp are same.
{
Console.Write("Palidrome Number");
}
else
{
Console.Write("Not a Palidrome Number");
}
}

Output

Addition of input numbers

public void SumOfNumber()
{
// sum of number => adding all the digits
int num, sum = 0;
Console.Write("Enter the number: ");
num = Convert.ToInt32(Console.ReadLine());
while (num >= 1)
{
sum = sum + num % 10;
num = num / 10;
}
Console.Write("Sum of Number: " + sum);
}

Output

Print the greatest common divisor (GCD) between two numbers

public void GCDNumber()
{
// GCD Number are known as Greatest Common Divisor
// number which is the largest number that divides both number
// Example
// 3 = 3
// 6 = 2 * 3
// So the GCD of 3 and 6 is: 3
int num1, num2;
Console.Write("Enter the First number: ");
num1 = Convert.ToInt32(Console.ReadLine());
Console.Write("Enter the second number: ");
num2 = Convert.ToInt32(Console.ReadLine());
while (num1 != num2) // numb1 not equal to num2
{
if (num1 > num2) // check num1 is greater than num2
{
num1 = num1 - num2; // subtract num2 form num1
}
else
{
num2 = num2 - num1; // else subtract num1 from num2
}
}
if (num1 == 1)
{
Console.Write("No GCD Number");
}
else
{
Console.Write("GCD Number: " + num1);
}
}

Output

Print the least common multiplier (LCM) between two numbers

public void LCMNumber()
{
// LCM Number are Least Common Multiplication
// LCM of two number is the smallest number (not zero) that is a multiple of both.
// 6 = 2 * 3
// 8 = 2 * 2 * 2
// So the GCD of 6 and 8 is: 24
int num1, num2, a, b, lcmNum;
Console.Write("Enter the First number: ");
num1 = Convert.ToInt32(Console.ReadLine());
Console.Write("Enter the second number: ");
num2 = Convert.ToInt32(Console.ReadLine());
a = num2;
b = num1;
while (num1 != num2) // check num1 is equal or not
{
if (num1 > num2) // check num1 is greater than num2
{
num1 = num1 - num2; // subtract num2 from num1 and save in num1
}
else
{
num2 = num2 - num1; // subtract num1 from num2 and save in num2
}
}
lcmNum = (a * b) / num1; // multiply the orinal two number and divide with num1
Console.Write("LCM number: " + lcmNum);
}

Output

Print table from 1 to 10

public void print1To10Table()
{
// Print table form 1 to 10
for (int num1 = 1; num1 <= 10; num1++)
{
for (int num2 = 1; num2 <= 10; num2++)
{
Console.Write(num1 * num2 + "\t");
}
Console.WriteLine("");
}
}

Output

Fibonacci Series of input numbers

public void FibonacciNumber()
{
// Fibonacci Series till number 10 is: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34
int num, firstNum = 0, secondNum = 1, temp, thirdNum = 3;
Console.Write("Enter the number: ");
num = Convert.ToInt32(Console.ReadLine());
Console.Write(firstNum + "\t" + secondNum); // print the first two number i.e 1 2
while (thirdNum <= num) // check enter number is less than third number i.e 3
{
temp = firstNum + secondNum; // add firstNum and secondNum and stored in temp
Console.Write("\t" + temp); // print the third numb
firstNum = secondNum; // assing secondNumb to firstNum
secondNum = temp; // assing temp number to secondNum
thirdNum = thirdNum + 1; // Increment the thirdNum
}
}

Output

Swap numbers using a third variable

public void SwapNumber()
{
// Swap Number
// Orginal Number: x = 2 and y = 3
// After Swapping: x = 3 and y = 2
// This method will swap number using temp variable
int num1, num2, temp;
Console.Write("Enter the First number: ");
num1 = Convert.ToInt32(Console.ReadLine());
Console.Write("Enter the second number: ");
num2 = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("Number Before Swap x: " + num1 + " y: " + num2);
temp = num2; // assign the second number to temp
num2 = num1; // assign the first number to second number
num1 = temp; // assign temp to second number
Console.WriteLine("Number After Swap x: " + num1 + " y: " + num2);
}

Output

Swap number without using a third variable

public void SwapNumberWithoutThirdVariable()
{
int num1, num2;
Console.Write("Enter the First number: ");
num1 = Convert.ToInt32(Console.ReadLine());
Console.Write("Enter the second number: ");
num2 = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("Number Before Swap x: " + num1 + " y: " + num2);
num1 = num1 + num2; // add num1 and num2
num2 = num1 - num2; // subtract num2 from num1 and assign to num2
num1 = num1 - num2; // subtract num2 form num1 and assign to num1
Console.WriteLine("Number After Swap x: " + num1 + " y: " + num2);
}

Output

Print tranpose of a 3 by 3 matrix

public void Print3By3MatrixTranspose()
{
// The transpose of a matrix is a new matrix whose rows are the columns of the original.
int[,] pos = new int[3, 3]; // declare multidimensional array which accepts 3 rows by 3 columns
int rows, cols; // initialize rows and columns
Console.WriteLine("Enter value for Matrix:");
for (rows = 0; rows < 3; rows++)
{
for (cols = 0; cols < 3; cols++)
{
pos[rows, cols] = Convert.ToInt32(Console.ReadLine()); // read the 9 digit in the matrix
}
}
Console.WriteLine("Original Matrix:");
for (rows = 0; rows < 3; rows++)
{
for (cols = 0; cols < 3; cols++)
{
Console.Write(pos[rows, cols] + "\t"); // print the original matrix
}
Console.WriteLine("");
}
Console.WriteLine("Transpose of Matrix:");
for (rows = 0; rows < 3; rows++)
{
for (cols = 0; cols < 3; cols++)
{
Console.Write(pos[cols, rows] + "\t"); // change the row to column
}
Console.WriteLine("");
}
}

Output

Matrix multiplication between two 3 by 3 matrices

public void Print3By3MatrixMultiplication()
{
/*
* Step 1: Make sure that the the number of columns in the 1st one equals the number of rows in the 2nd one. (The pre-requisite to be able to multiply)
* Step 2: Multiply the elements of each row of the first matrix by the elements of each column in the second matrix.
* Step 3: Add the products.
*
* Example: Below matrix will be denoted as per following symbols
*
* FirstMatrix = fm
* SecondMatrix = sm
* ResultMatrix = rm
*
* rm[0,0] = fm[0,0]*sm[0,0] + fm[0,1]*sm[1,0] + fm[0,3]*sm[2,0]
* rm[0,1] = fm[0,0]*sm[0,1] + fm[0,1]*sm[1,1] + fm[0,0]*sm[2,1]
* rm[0,2] = fm[0,0]*sm[0,2] + fm[0,1]*sm[1,2] + fm[0,0]*sm[2,2]
* *
* *
* *
* rm[2,2] = fm[2,0]*sm[0,2] + fm[2,1]*sm[1,2] + fm[2,2]*sm[2,2]
*/
// declare 3 multidimensional array
int[,] fm = new int[3, 3];
int[,] sm = new int[3, 3];
int[,] rm = new int[3, 3];
int rows, cols, temp, rowTemp;
Console.WriteLine("Enter value for Matrix 1: ");
for (rows = 0; rows < 3; rows++)
{
for (cols = 0; cols < 3; cols++)
{
fm[rows, cols] = Convert.ToInt32(Console.ReadLine()); // Read first matrix value and store into fm array
}
}
Console.WriteLine("Enter value for Matrix 2: ");
for (rows = 0; rows < 3; rows++)
{
for (cols = 0; cols < 3; cols++)
{
sm[rows, cols] = Convert.ToInt32(Console.ReadLine()); // Read secnd matrix value and store into sm
}
}
Console.WriteLine("Original Matrix 1:");
for (rows = 0; rows < 3; rows++)
{
for (cols = 0; cols < 3; cols++)
{
Console.Write(fm[rows, cols] + "\t"); // Print first matrix
}
Console.WriteLine("");
}
Console.WriteLine("Original Matrix 2:");
for (rows = 0; rows < 3; rows++)
{
for (cols = 0; cols < 3; cols++)
{
Console.Write(sm[rows, cols] + "\t"); // print second matrix
}
Console.WriteLine("");
}
for (rows = 0; rows < 3; rows++)
{
for (cols = 0; cols < 3; cols++)
{
for (rowTemp = 0, temp = 0; temp < 3; temp++)
{
rowTemp = rowTemp + fm[rows, temp] * sm[temp, cols]; // fm[0,0]*sm[0,0] + fm[0,1]*sm[1,0] + fm[0,3]*sm[2,0]
}
rm[rows, cols] = rowTemp;// rm[0,0] = rowTemp
}
}
Console.WriteLine("Multiplication of 2 Matrix is:");
for (rows = 0; rows < 3; rows++)
{
for (cols = 0; cols < 3; cols++)
{
Console.Write(rm[rows, cols] + "\t"); // Print the result matrix.
}
Console.WriteLine("");
}
}