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

  1. public void OddEvenNumber()
  2. {
  3. // Number which is divisible by 2 is known as Even number
  4. // Number which is not divisible by 2 is known as Odd number
  5. Console.Write("Enter the number: ");
  6. int number = Convert.ToInt32(Console.ReadLine());
  7. if (number % 2 == 0) // check number after division is zero
  8. {
  9. Console.Write(number + " is Even Number"); // If divisible by number
  10. }
  11. else
  12. {
  13. Console.Write(number + " is Odd number"); // if not divisble by number
  14. }
  15. }
Output
Number Series Codes Using C#

Check Prime Number

  1. public void PrimeNumber()
  2. {
  3. // Prime numbers are numbers divisible by 1 and itself.
  4. Console.Write("Enter the number: ");
  5. int number = Convert.ToInt32(Console.ReadLine());
  6. int i, m = 0, count = 0;
  7. m = number / 2;
  8. for (i = 2; i <= m; i++) // check number is divisible by any another number
  9. {
  10. if (number % i == 0) // If number is divisible by another number
  11. {
  12. count = 1; // reassign the count to 1
  13. break; // break the for loop
  14. }
  15. }
  16. if (number > 1 && count == 0) // number should be greater than 1.
  17. {
  18. Console.Write(number + " is prime number");
  19. }
  20. else
  21. {
  22. Console.Write(number + " is non prime number");
  23. }
  24. }
Output
Number Series Codes Using C#


Print prime number from 1 to 100

  1. public void PrintPrimeNumber1To100()
  2. {
  3. // Prime number are the number which is divisible by 1 or itself.
  4. bool isPrimeNumber = true; // check number is prime number
  5. int outerloop, innerloop; // declare to
  6. Console.WriteLine("Prime Numbers are : ");
  7. for (outerloop = 2; outerloop <= 100; outerloop++)
  8. {
  9. for (innerloop= 2; innerloop <= 100; innerloop++)
  10. {
  11. if (outerloop != innerloop && outerloop % innerloop== 0)
  12. {
  13. isPrimeNumber = false;
  14. break;
  15. }
  16. }
  17. if (isPrimeNumber) // If number is prime number print them on console.
  18. {
  19. Console.Write("\t" + outerloop);
  20. }
  21. isPrimeNumber = true;
  22. }
  23. Console.ReadLine();
  24. }
Output
Number Series Codes Using C#

Print factorial of input number

  1. public void Factorial()
  2. {
  3. // Factorial of number 4 is: 4*3*2*1 = 24
  4. int num, factorial = 1;
  5. Console.Write("Enter the number: ");
  6. num = Convert.ToInt32(Console.ReadLine());
  7. while (num >= 1) // check number is greater or equal to 1
  8. {
  9. factorial = factorial * num; // multiply the number
  10. num--; // decrement the number by 1
  11. }
  12. Console.Write("Factorial: " + factorial);
  13. }
Output
Number Series Codes Using C#

Print the reverse number of input number

  1. public void ReverseNumber()
  2. {
  3. // ReverseNumber
  4. int originalNumber, reverseNumber = 0;
  5. Console.Write("Enter the number: ");
  6. originalNumber = Convert.ToInt32(Console.ReadLine());
  7. while (originalNumber >= 1)
  8. {
  9. reverseNumber = reverseNumber * 10 + originalNumber % 10; // multiply the reverseNumber with 10 and modulus on orginal number
  10. originalNumber = originalNumber / 10;
  11. }
  12. Console.Write("Reverse Number: " + reverseNumber);
  13. }
Output
Number Series Codes Using C#

Check if input number is palidrome or not

  1. public void CheckPalidromeNumber()
  2. {
  3. // Palidrome number is number that remains same when its digit are reversed.
  4. int numb, temp = 0, orginalNumb;
  5. Console.Write("Enter the number: ");
  6. numb = Convert.ToInt32(Console.ReadLine());
  7. orginalNumb = numb; // store the entered number into original number
  8. while (numb >= 1)
  9. {
  10. temp = temp * 10 + numb % 10;
  11. numb = numb / 10;
  12. }
  13. if (temp == orginalNumb) // check orginal number and temp are same.
  14. {
  15. Console.Write("Palidrome Number");
  16. }
  17. else
  18. {
  19. Console.Write("Not a Palidrome Number");
  20. }
  21. }
Output
Number Series Codes Using C#

Addition of input numbers

  1. public void SumOfNumber()
  2. {
  3. // sum of number => adding all the digits
  4. int num, sum = 0;
  5. Console.Write("Enter the number: ");
  6. num = Convert.ToInt32(Console.ReadLine());
  7. while (num >= 1)
  8. {
  9. sum = sum + num % 10;
  10. num = num / 10;
  11. }
  12. Console.Write("Sum of Number: " + sum);
  13. }
Output
Number Series Codes Using C#

Print the greatest common divisor (GCD) between two numbers

  1. public void GCDNumber()
  2. {
  3. // GCD Number are known as Greatest Common Divisor
  4. // number which is the largest number that divides both number
  5. // Example
  6. // 3 = 3
  7. // 6 = 2 * 3
  8. // So the GCD of 3 and 6 is: 3
  9. int num1, num2;
  10. Console.Write("Enter the First number: ");
  11. num1 = Convert.ToInt32(Console.ReadLine());
  12. Console.Write("Enter the second number: ");
  13. num2 = Convert.ToInt32(Console.ReadLine());
  14. while (num1 != num2) // numb1 not equal to num2
  15. {
  16. if (num1 > num2) // check num1 is greater than num2
  17. {
  18. num1 = num1 - num2; // subtract num2 form num1
  19. }
  20. else
  21. {
  22. num2 = num2 - num1; // else subtract num1 from num2
  23. }
  24. }
  25. if (num1 == 1)
  26. {
  27. Console.Write("No GCD Number");
  28. }
  29. else
  30. {
  31. Console.Write("GCD Number: " + num1);
  32. }
  33. }
Output
Number Series Codes Using C#

Print the least common multiplier (LCM) between two numbers

  1. public void LCMNumber()
  2. {
  3. // LCM Number are Least Common Multiplication
  4. // LCM of two number is the smallest number (not zero) that is a multiple of both.
  5. // 6 = 2 * 3
  6. // 8 = 2 * 2 * 2
  7. // So the GCD of 6 and 8 is: 24
  8. int num1, num2, a, b, lcmNum;
  9. Console.Write("Enter the First number: ");
  10. num1 = Convert.ToInt32(Console.ReadLine());
  11. Console.Write("Enter the second number: ");
  12. num2 = Convert.ToInt32(Console.ReadLine());
  13. a = num2;
  14. b = num1;
  15. while (num1 != num2) // check num1 is equal or not
  16. {
  17. if (num1 > num2) // check num1 is greater than num2
  18. {
  19. num1 = num1 - num2; // subtract num2 from num1 and save in num1
  20. }
  21. else
  22. {
  23. num2 = num2 - num1; // subtract num1 from num2 and save in num2
  24. }
  25. }
  26. lcmNum = (a * b) / num1; // multiply the orinal two number and divide with num1
  27. Console.Write("LCM number: " + lcmNum);
  28. }
Output
Number Series Codes Using C#

Print table from 1 to 10

  1. public void print1To10Table()
  2. {
  3. // Print table form 1 to 10
  4. for (int num1 = 1; num1 <= 10; num1++)
  5. {
  6. for (int num2 = 1; num2 <= 10; num2++)
  7. {
  8. Console.Write(num1 * num2 + "\t");
  9. }
  10. Console.WriteLine("");
  11. }
  12. }
Output
Number Series Codes Using C#

Fibonacci Series of input numbers

  1. public void FibonacciNumber()
  2. {
  3. // Fibonacci Series till number 10 is: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34
  4. int num, firstNum = 0, secondNum = 1, temp, thirdNum = 3;
  5. Console.Write("Enter the number: ");
  6. num = Convert.ToInt32(Console.ReadLine());
  7. Console.Write(firstNum + "\t" + secondNum); // print the first two number i.e 1 2
  8. while (thirdNum <= num) // check enter number is less than third number i.e 3
  9. {
  10. temp = firstNum + secondNum; // add firstNum and secondNum and stored in temp
  11. Console.Write("\t" + temp); // print the third numb
  12. firstNum = secondNum; // assing secondNumb to firstNum
  13. secondNum = temp; // assing temp number to secondNum
  14. thirdNum = thirdNum + 1; // Increment the thirdNum
  15. }
  16. }
Output
Number Series Codes Using C#

Swap numbers using a third variable

  1. public void SwapNumber()
  2. {
  3. // Swap Number
  4. // Orginal Number: x = 2 and y = 3
  5. // After Swapping: x = 3 and y = 2
  6. // This method will swap number using temp variable
  7. int num1, num2, temp;
  8. Console.Write("Enter the First number: ");
  9. num1 = Convert.ToInt32(Console.ReadLine());
  10. Console.Write("Enter the second number: ");
  11. num2 = Convert.ToInt32(Console.ReadLine());
  12. Console.WriteLine("Number Before Swap x: " + num1 + " y: " + num2);
  13. temp = num2; // assign the second number to temp
  14. num2 = num1; // assign the first number to second number
  15. num1 = temp; // assign temp to second number
  16. Console.WriteLine("Number After Swap x: " + num1 + " y: " + num2);
  17. }
Output
Number Series Codes Using C#

Swap number without using a third variable

  1. public void SwapNumberWithoutThirdVariable()
  2. {
  3. int num1, num2;
  4. Console.Write("Enter the First number: ");
  5. num1 = Convert.ToInt32(Console.ReadLine());
  6. Console.Write("Enter the second number: ");
  7. num2 = Convert.ToInt32(Console.ReadLine());
  8. Console.WriteLine("Number Before Swap x: " + num1 + " y: " + num2);
  9. num1 = num1 + num2; // add num1 and num2
  10. num2 = num1 - num2; // subtract num2 from num1 and assign to num2
  11. num1 = num1 - num2; // subtract num2 form num1 and assign to num1
  12. Console.WriteLine("Number After Swap x: " + num1 + " y: " + num2);
  13. }
Output
Number Series Codes Using C#

Print tranpose of a 3 by 3 matrix

  1. public void Print3By3MatrixTranspose()
  2. {
  3. // The transpose of a matrix is a new matrix whose rows are the columns of the original.
  4. int[,] pos = new int[3, 3]; // declare multidimensional array which accepts 3 rows by 3 columns
  5. int rows, cols; // initialize rows and columns
  6. Console.WriteLine("Enter value for Matrix:");
  7. for (rows = 0; rows < 3; rows++)
  8. {
  9. for (cols = 0; cols < 3; cols++)
  10. {
  11. pos[rows, cols] = Convert.ToInt32(Console.ReadLine()); // read the 9 digit in the matrix
  12. }
  13. }
  14. Console.WriteLine("Original Matrix:");
  15. for (rows = 0; rows < 3; rows++)
  16. {
  17. for (cols = 0; cols < 3; cols++)
  18. {
  19. Console.Write(pos[rows, cols] + "\t"); // print the original matrix
  20. }
  21. Console.WriteLine("");
  22. }
  23. Console.WriteLine("Transpose of Matrix:");
  24. for (rows = 0; rows < 3; rows++)
  25. {
  26. for (cols = 0; cols < 3; cols++)
  27. {
  28. Console.Write(pos[cols, rows] + "\t"); // change the row to column
  29. }
  30. Console.WriteLine("");
  31. }
  32. }
Output
Number Series Codes Using C#

Matrix multiplication between two 3 by 3 matrices

  1. public void Print3By3MatrixMultiplication()
  2. {
  3. /*
  4. * 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)
  5. * Step 2: Multiply the elements of each row of the first matrix by the elements of each column in the second matrix.
  6. * Step 3: Add the products.
  7. *
  8. * Example: Below matrix will be denoted as per following symbols
  9. *
  10. * FirstMatrix = fm
  11. * SecondMatrix = sm
  12. * ResultMatrix = rm
  13. *
  14. * rm[0,0] = fm[0,0]*sm[0,0] + fm[0,1]*sm[1,0] + fm[0,3]*sm[2,0]
  15. * rm[0,1] = fm[0,0]*sm[0,1] + fm[0,1]*sm[1,1] + fm[0,0]*sm[2,1]
  16. * rm[0,2] = fm[0,0]*sm[0,2] + fm[0,1]*sm[1,2] + fm[0,0]*sm[2,2]
  17. * *
  18. * *
  19. * *
  20. * rm[2,2] = fm[2,0]*sm[0,2] + fm[2,1]*sm[1,2] + fm[2,2]*sm[2,2]
  21. */
  23. // declare 3 multidimensional array
  24. int[,] fm = new int[3, 3];
  25. int[,] sm = new int[3, 3];
  26. int[,] rm = new int[3, 3];
  27. int rows, cols, temp, rowTemp;
  28. Console.WriteLine("Enter value for Matrix 1: ");
  29. for (rows = 0; rows < 3; rows++)
  30. {
  31. for (cols = 0; cols < 3; cols++)
  32. {
  33. fm[rows, cols] = Convert.ToInt32(Console.ReadLine()); // Read first matrix value and store into fm array
  34. }
  35. }
  36. Console.WriteLine("Enter value for Matrix 2: ");
  37. for (rows = 0; rows < 3; rows++)
  38. {
  39. for (cols = 0; cols < 3; cols++)
  40. {
  41. sm[rows, cols] = Convert.ToInt32(Console.ReadLine()); // Read secnd matrix value and store into sm
  42. }
  43. }
  44. Console.WriteLine("Original Matrix 1:");
  45. for (rows = 0; rows < 3; rows++)
  46. {
  47. for (cols = 0; cols < 3; cols++)
  48. {
  49. Console.Write(fm[rows, cols] + "\t"); // Print first matrix
  50. }
  51. Console.WriteLine("");
  52. }
  53. Console.WriteLine("Original Matrix 2:");
  54. for (rows = 0; rows < 3; rows++)
  55. {
  56. for (cols = 0; cols < 3; cols++)
  57. {
  58. Console.Write(sm[rows, cols] + "\t"); // print second matrix
  59. }
  60. Console.WriteLine("");
  61. }
  63. for (rows = 0; rows < 3; rows++)
  64. {
  65. for (cols = 0; cols < 3; cols++)
  66. {
  67. for (rowTemp = 0, temp = 0; temp < 3; temp++)
  68. {
  69. 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]
  70. }
  71. rm[rows, cols] = rowTemp;// rm[0,0] = rowTemp
  72. }
  73. }
  74. Console.WriteLine("Multiplication of 2 Matrix is:");
  75. for (rows = 0; rows < 3; rows++)
  76. {
  77. for (cols = 0; cols < 3; cols++)
  78. {
  79. Console.Write(rm[rows, cols] + "\t"); // Print the result matrix.
  80. }
  81. Console.WriteLine("");
  82. }
  84. }
Output
Number Series Codes Using C#

Triangle number pyramid

Print the number pyramid which looks like following,
1
2 2
3 3 3
  1. public void TrianglePyramidNumber()
  2. {
  3. // print the Triangle pyaramid for 9 digit
  4. int rows, cols, temp, space = 8;
  5. for (rows = 1; rows <= 9; rows++)
  6. {
  7. for (cols = space; cols >= 1; cols--)
  8. {
  9. Console.Write(" "); // print space
  10. }
  11. for (temp = 1; temp <= rows; temp++)
  12. {
  13. Console.Write(rows + " "); // print rows value
  14. }
  15. Console.WriteLine("");
  16. space--;
  17. }
  18. }
Output
Number Series Codes Using C#

Print the number pyramid where the numbers start from the left side.

  1. public void leftPyramidNumber()
  2. {
  3. // Start the pyramid from left side.
  4. int rows, cols;
  5. for (rows = 1; rows <= 9; rows++)
  6. {
  7. for (cols = 1; cols <= rows; cols++)
  8. {
  9. Console.Write(rows + " "); // print rows value
  10. }
  11. Console.WriteLine("");
  12. }
  13. }
Output
Number Series Codes Using C#

Print the number pyramid where numbers start from the right side.

  1. public void RightPyramidNumber()
  2. {
  3. // start the pyramid from right side
  4. int rows, cols;
  5. for (rows = 1; rows <= 9; rows++)
  6. {
  7. for (cols = 1; cols <= 9 - rows; cols++)
  8. {
  9. Console.Write("\t"); // print number of space row - 1 = 9-1 => 8
  10. }
  11. for (cols = 1; cols <= rows; cols++)
  12. {
  13. Console.Write(rows + "\t"); // print rows value.
  14. }
  15. Console.WriteLine("");
  16. }
  18. }
Output
Number Series Codes Using C#
Find the source code as an attachment.