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## Primitive data types for real numbers: double

Besides the types for representing integer numbers, in Java there are two primitive data types for representing real numbers. Due to the way in which real numbers are represented internally in memory, these numbers are also called floating point numbers.

The data type for floating point numbers that is used by default in the Java mathematical library is double.

 Type double Dimension 64 bit (8 byte) Domain set of 264 positive and Minimum absolute value 1.79769313486231570 . 10-308 negative real numbers Maximum absolute value 2.250738585072014 . 10+308 Precision 15 decimal digits Operations + sum - difference * product / division Literals sequences of digits with decimal dot optionally ending with a d (or D) denoting values of the domain (e.g., 3.14 or 3.14d) representation in scientific notation (e.g., 314E-2 or 314E-2d)

Example:

double pi, p2;  // Declaration of variables of type double
pi = 3.14;      // Use of literals
p2 = 628E-2d;   // Use of literals
p2 = pi * 2;    // Arithmetic expression


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