Main rule is never to use float, because of unwanted effetcs:

Here the version with decimal. It always is correct.

DECLARE @SumA float, @SumB float

DECLARE @MyFloat1 float, @MyFloat2 float, @MyFloat3 float

DECLARE @MyTable table

(

ID int primary key identity,

NumA DECIMAL(17,0),

NumB DECIMAL(17,0)

)

SET @MyFloat1 = 10000000000020000

SET @MyFloat2 = -10000000000010000

SET @MyFloat3 = 1

INSERT INTO @MyTable

SELECT @MyFloat1, CAST(@MyFloat3 AS FLOAT)

UNION

SELECT @MyFloat2, @MyFloat1

UNION ALL

SELECT @MyFloat3, @MyFloat2

SELECT SUM(NumA), SUM(NumB) FROM

(select top 100 * from @MyTable

order by 1

) AS A

SELECT SUM(NumA), SUM(NumB) FROM

(select top 100 * from @MyTable

order by 2

) AS B