The %Calculate%1+2% token returns the result of performing a calculation.
This allows you to include any function in a text field.
Remember that within a calculation you can use variables unadorned. So for a variable “Count” that has a numerical value, these two are roughly equivalent in a text field:
A notable different would be if the variable had a value like “1.230”. Then the result of the %Calculate% would be “1.23”.