I'm playing around with your math versions, and I'm not getting quite the result I expected. Did I misinterpret what you had in mind?

-----------

CREATE FUNCTION dbo.BitClear(@nvalue BigInt, @nposition TinyInt) 

RETURNS BigInt AS 

BEGIN

Declare @nResult Bigint

set @nResult = @nValue  ^ Power( 2, @nPosition)

Return @nResult

END

CREATE FUNCTION dbo.BitSet(@nvalue BigInt, @nposition TinyInt) 

RETURNS BigInt AS 

BEGIN

Declare @nResult Bigint

set @nResult = @nValue | Power( 2, (@nPosition))

Return @nResult

END

-----------

now when I try to use them, I get the expected results for positions 0 and 1, but both functions give me identical results for positions 3 +

Declare @Cleared BigInt

Declare @Set BigInt

Declare @test-2 BigInt

Set @test-2 = 67

Set @cleared = dbo.BitClear(@test,3)

Set @set = dbo.BitSet(@test,3)

Select

@test-2,@cleared,@set,

 fn_replinttobitstring(@test),

 fn_replinttobitstring(@cleared),

 fn_replinttobitstring(@set)