float (C# Reference)
The float keyword signifies a simple type that stores 32bit floatingpoint values. The following table shows the precision and approximate range for the float type.
Type 
Approximate range 
Precision 
.NET Framework type 

float 
3.4 × 1038to +3.4 × 1038 
7 digits 
By default, a real numeric literal on the right side of the assignment operator is treated as double. Therefore, to initialize a float variable, use the suffix f or F, as in the following example:
float x = 3.5F;
If you do not use the suffix in the previous declaration, you will get a compilation error because you are trying to store a double value into a float variable.
You can mix numeric integral types and floatingpoint types in an expression. In this case, the integral types are converted to floatingpoint types. The evaluation of the expression is performed according to the following rules:

If one of the floatingpoint types is double, the expression evaluates to double or bool in relational or Boolean expressions.

If there is no double type in the expression, the expression evaluates to float or bool in relational or Boolean expressions.
A floatingpoint expression can contain the following sets of values:

Positive and negative zero

Positive and negative infinity

NotaNumber value (NaN)

The finite set of nonzero values
For more information about these values, see IEEE Standard for Binary FloatingPoint Arithmetic, available on the IEEE Web site.
In the following example, an int, a short, and a float are included in a mathematical expression giving a float result. (Remember that float is an alias for the System.Single type.) Notice that there is no double in the expression.
class FloatTest { static void Main() { int x = 3; float y = 4.5f; short z = 5; var result = x * y / z; Console.WriteLine("The result is {0}", result); Type type = result.GetType(); Console.WriteLine("result is of type {0}", type.ToString()); } } /* Output: The result is 2.7 result is of type System.Single //'float' is alias for 'Single' */
For more information, see the C# Language Specification. The language specification is the definitive source for C# syntax and usage.