From QB64.org wiki
Syntax: return_value = number1 + number2
- A + sign also can indicate a positive numerical value, but it is not required.
- Numbers used can be any literal or variable numerical value type.
- Adding one negative value will actually perform subtraction on the other value.
- Adding two negative values will make the return value more negative.
- Addition and subtraction are the last operations performed in Qbasic's normal order of operations.
- The plus(+) operator can also be used to add (concatenate) literal or variable STRING values.
- PRINT can also use + operations on string values ONLY! Numerical values will need to be converted to strings first or be included using semicolons or commas instead.