What are the main differences between Double and Decimal data types in storing numerical values?

The main differences between the Double and Decimal types in C# are related to precision and application scope:

• Double is a 64-bit double-precision floating-point number (IEEE 754). It stores approximate values and is suitable for scientific calculations where speed and a large range are important, but precision after the decimal point is not critical.

• Decimal is a 128-bit fixed-precision number designed for financial and monetary calculations where high accuracy and no rounding errors are important.

Example:

double a = 0.1 + 0.2; // may be 0.30000000000000004
decimal b = 0.1m + 0.2m; // exactly 0.3

Thus, Decimal is better for monetary amounts, while Double is suitable for scientific and engineering calculations.