Msg 102, Level 15, State 1 Error

I am writing a user defined function but I am receiving an error message that I can figure out. Any answers out there?

Msg 102, Level 15, State 1, Procedure ufn_GetStreetNumber, Line 25
Incorrect syntax near '@StreetNum'.

-- ---------------------------------------------------------------------------------
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Description: Parses out the Street number for Address field
-- =============================================
CREATE FUNCTION dbo.ufn_GetStreetNumber
(
-- Add the parameters for the function here
@StreetAddr varchar(50)
)
RETURNS int
AS
BEGIN
-- Declare the return variable here
DECLARE @StreetNum varchar(50);
DECLARE @iIter smallint, @iNoOfChars smallint, @iStreetNo int;

SET @StreetNum=NULL;
SET @iStreetNo=0;
SET @iNoOfChars=1;
SET @iIter=1;

-- Add the T-SQL statements to compute the return value here
WHILE Isnumeric(Substring(@StreetAddr,@iNoOfChars,@iIter))=1
@StreetNum=@StreetNum + Substring(@StreetAddr,@iNoOfChars,@iIter)
@iIter=@iIter+1
BREAK
@iStreetNo=@StreetNum

-- Return the result of the function
RETURN @iStreetNo

END
GO