Manipulate decimals with numeric operators in C#

The decimal data type in C# provides precise arithmetic operations for financial and monetary calculations. You can manipulate decimals using standard numeric operators such as +, -, *, /, and %.

Decimal literals in C# must be suffixed with M or m to distinguish them from double values. This ensures precision is maintained during calculations.

Syntax

Following is the syntax for declaring decimal variables −

decimal variableName = value M;

Following is the syntax for basic arithmetic operations with decimals −

decimal result = decimal1 + decimal2;  // Addition
decimal result = decimal1 - decimal2;  // Subtraction
decimal result = decimal1 * decimal2;  // Multiplication
decimal result = decimal1 / decimal2;  // Division
decimal result = decimal1 % decimal2;  // Modulus

Basic Arithmetic Operations

Example

using System;

class Demo {
   static void Main() {
      decimal d1 = 9.5M;
      decimal d2 = 4.2M;
      
      decimal addition = d1 + d2;
      Console.WriteLine("Addition: " + addition);
      
      decimal subtraction = d1 - d2;
      Console.WriteLine("Subtraction: " + subtraction);
      
      decimal multiplication = d1 * d2;
      Console.WriteLine("Multiplication: " + multiplication);
      
      decimal division = d1 / d2;
      Console.WriteLine("Division: " + division);
   }
}

The output of the above code is −

Addition: 13.7
Subtraction: 5.3
Multiplication: 39.90
Division: 2.2619047619047619047619047619

Using Compound Assignment Operators

C# provides compound assignment operators that combine arithmetic operations with assignment −

Example

using System;

class Demo {
   static void Main() {
      decimal balance = 1000.50M;
      Console.WriteLine("Initial balance: " + balance);
      
      balance += 250.75M;  // Equivalent to: balance = balance + 250.75M
      Console.WriteLine("After deposit: " + balance);
      
      balance -= 125.25M;  // Equivalent to: balance = balance - 125.25M
      Console.WriteLine("After withdrawal: " + balance);
      
      balance *= 1.05M;    // Apply 5% interest
      Console.WriteLine("After interest: " + balance);
   }
}

The output of the above code is −

Initial balance: 1000.50
After deposit: 1251.25
After withdrawal: 1126.00
After interest: 1182.30

Comparison and Modulus Operations

Example

using System;

class Demo {
   static void Main() {
      decimal price1 = 15.99M;
      decimal price2 = 12.50M;
      decimal taxRate = 0.08M;
      
      // Comparison operations
      Console.WriteLine("Price1 > Price2: " + (price1 > price2));
      Console.WriteLine("Price1 == Price2: " + (price1 == price2));
      
      // Modulus operation
      decimal remainder = price1 % 5.0M;
      Console.WriteLine("Remainder when price1 divided by 5: " + remainder);
      
      // Tax calculation
      decimal tax = price1 * taxRate;
      decimal total = price1 + tax;
      Console.WriteLine("Price: " + price1 + ", Tax: " + tax + ", Total: " + total);
   }
}

The output of the above code is −

Price1 > Price2: True
Price1 == Price2: False
Remainder when price1 divided by 5: 0.99
Price: 15.99, Tax: 1.2792, Total: 17.2692

Key Advantages of Decimal Type

Conclusion

The decimal data type in C# supports all standard arithmetic operators and provides precise calculations essential for financial applications. Always use the M suffix when declaring decimal literals to ensure proper type assignment and maintain precision in your calculations.