Returns the combined text and numbers specified by text, with the numbers in text incremented by the specified amount.
text - any text that also contains a number
incrementBy - any numeric expression to increment the text by
Data type returned 
Originated in 
FileMaker Pro 7.0
This function doesn’t remove the text in text, which normally happens when performing standard math against a value that contains text.
If the incrementBy value is a decimal number, then only the integer portion of incrementBy value is added to the last number in text. Any character other than a number is considered a separator. You can use both positive and negative incrementBy values.
SerialIncrement(“abc12”;1) returns abc13.
SerialIncrement(“abc12”;7) returns abc19.
SerialIncrement(“abc12”;-1) returns abc11.
SerialIncrement(“abc12”;1.2) returns abc13.
SerialIncrement(“abc1.2”;1.2) returns abc1.3.
In the example below any character other than a number is considered as a separator and the number on the far right is incremented.
SerialIncrement(“abc123;999”;1) returns abc123;1000.
Related topics 
Functions reference (category list)
Functions reference (alphabetical list)
About formulas
About functions
Defining calculation fields
Using operators in formulas