What Is Decimal Data Type in C#?


Heather Bennett

The Decimal data type in C# is a built-in numeric data type that is used to store decimal numbers with high precision and a wide range of values. It is particularly useful when dealing with financial calculations or any situation where precision is crucial.

Unlike other numeric data types such as int or float, the Decimal data type provides a higher level of precision and accuracy. It can store decimal numbers with up to 28-29 significant digits, compared to the limited range of other numeric types.

To declare a variable of type Decimal, you can use the following syntax:

Decimal myDecimalVariable;

You can also assign a value to a Decimal variable at the time of declaration:

Decimal myDecimalVariable = 3.14159M;

The ‘M’ at the end of the number is necessary to indicate that it should be treated as a decimal literal.

One important thing to note about the Decimal data type is that it is a value type, which means that when you assign a Decimal variable to another, it creates a copy of the value rather than referencing the same memory location.

Precision and Accuracy:

The main advantage of using the Decimal data type over other numeric types like float or double is its precision. Decimal numbers are stored as integers scaled by a power of 10. This allows for precise representation of decimal fractions without any loss of information.

For example, consider the following code snippet:

decimal firstNumber = 1.2345678901234567890123456M;
decimal secondNumber = 0.000000000000000000000001M;
decimal sum = firstNumber + secondNumber;

In this case, the Decimal data type ensures that the sum of these two numbers is calculated accurately, resulting in the expected output of 1.2345678901234567890123457.

However, if we were to use a float or double data type instead, we would encounter a loss of precision due to their limited number of significant digits.

Arithmetic Operations:

The Decimal data type supports all common arithmetic operations such as addition, subtraction, multiplication, and division. These operations can be performed using the standard arithmetic operators (+,-,*,/) or predefined methods available for Decimal.

Here’s an example that demonstrates some arithmetic operations using the Decimal data type:

decimal num1 = 10.5M;
decimal num2 = 2.5M;

decimal sum = num1 + num2;
decimal difference = num1 – num2;
decimal product = num1 * num2;
decimal quotient = num1 / num2;

Console.WriteLine(“Sum: ” + sum);
Console.WriteLine(“Difference: ” + difference);
Console.WriteLine(“Product: ” + product);
Console.WriteLine(“Quotient: ” + quotient);


When working with decimal numbers, it is often necessary to round them to a specific number of decimal places. The Decimal data type provides various rounding methods that can be used for this purpose.

For example:

decimal number = 3.14159M;
decimal roundedNumber = Math.Round(number, 2); // Rounds to 2 decimal places


The output of this code will be 3.14, as the Math.Round() method rounds the number to the nearest value with two decimal places.


The Decimal data type in C# is a powerful tool for working with decimal numbers that require high precision and accuracy. Its ability to store a wide range of values with up to 28-29 significant digits makes it an ideal choice for financial calculations and other applications where precision is crucial.

By using the Decimal data type, you can ensure that your calculations are accurate and avoid any loss of precision that may occur with other numeric types. Incorporating the Decimal data type into your C# programs will enable you to handle decimal numbers reliably and precisely.

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