Bank Account Modulo 11 check

CREATE FUNCTION checkModulo11 (@BANKACNO BIGINT)
RETURNS VARCHAR(25)
AS
BEGIN
    --DECLARE @BANKACNO BIGINT
    DECLARE @CTR INT
    DECLARE @EXTRACT INT
    DECLARE @TOTAL INT
    DECLARE @MSG VARCHAR(25)

    SELECT @MSG = 'INVALID BANK A/C NUMBER'
    --SET @BANKACNO = 972428577 -- VALID
    --SET @BANKACNO = 972428575 -- INVALID
    SET @CTR = 0
    SET @TOTAL = 0
    WHILE @BANKACNO > 1
        BEGIN
        SET @CTR = @CTR+1
        SET @EXTRACT = @BANKACNO%10
        SET @BANKACNO = @BANKACNO/10
            --@TOTAL = @TOTAL + (@CTR * @EXTRACT)
            SELECT @TOTAL = @TOTAL + @CTR*@EXTRACT
        END
    IF (SELECT @TOTAL % 11) = 0
        BEGIN
            SELECT @MSG = 'VALID BANK A/C NUMBER' --AS ACCONT_NO_VALIDITY --MAY EVEN BE SELECT TRUE
        END

    --CHECKED MINE AND ITS VALID :)
    RETURN @MSG
END
GO

SELECT dbo.checkModulo11(972428567) AS BANK_AC_NO_VALIDITY --CAN BE WITH INT 1 OR O AND CASE TO SHOW VALIDITY

DROP FUNCTION checkModulo11