ColdFusion supports integers between -2,147,483,648 and 2,147,483,647 (32-bit signed integers). You can assign a value outside this range to a variable, but ColdFusion initially stores the number as a string. If you use it in an arithmetic expression, ColdFusion converts it into a floating-point value, preserving its value, but losing precision as the following example shows:

<cfset mybignum=12345678901234567890> 
<cfset mybignumtimes10=(mybignum * 10)> 
<cfoutput>mybignum is: #mybignum#</cfoutput><br> 
<cfoutput>mybignumtimes10 is: #mybignumtimes10# </cfoutput><br>

This example generates the following output:

mybignum is: 12345678901234567890

mybignumtimes10 is: 1.23456789012E+020

Real numbers, numbers with a decimal part, are also known as floating point numbers. ColdFusion real numbers can range from approximately -10300 to approximately 10300. A real number can have up to 12 significant digits. As with integers, you can assign a variable a value with more digits, but the data is stored as a string. The string is converted to a real number, and can lose precision, when you use it in an arithmetic expression.

You can represent real numbers in scientific notation. This format is xEy, where x is a positive or negative real number in the range 1.0 (inclusive) to 10 (exclusive), and y is an integer. The value of a number in scientific notation is x times 10y. For example, 4.0E² is 4.0 times 10², which equals 400. Similarly, 2.5E^-2 is 2.5 times 10^-2, which equals 0.025. Scientific notation is useful for writing very large and very small numbers.

ColdFusion does not have a special BigDecimal data type for arbitrary length decimal numbers such as 1234567890987564.234678503059281. Instead, it represents such numbers as strings. ColdFusion does, however, have a PrecisionEvaluate function that can take an arithmetic expression that uses BigDecimal values, calculate the expression, and return a string with the resulting BigDecimal value. For more information, see PrecisionEvaluate in the CFML Reference.