PRINT 'Define Table';
CREATE TABLE  #Quantities  (
 ID INT IDENTITY,
 DataSource varchar(30) NOT NULL,
 QF1 Float,
 QF2 Float,
 QTot AS QF1 + QF2,
 PF1 AS QF1 / (QF1 + QF2),
 PF2 AS QF2 / (QF1 + QF2) );

CREATE NONCLUSTERED INDEX IXC1 on #Quantities(ID) INCLUDE(PF1,PF2)

PRINT 'Insert data'; 
INSERT INTO #Quantities (DataSource, QF1, QF2)
SELECT 'Test 1' , 66, 34;

Print 'Insert Zeroes';
INSERT INTO #Quantities (DataSource, QF1, QF2)
SELECT 'Test 2', 0, 0;

Print 'Insert Nulls';
INSERT INTO #Quantities (DataSource, QF1, QF2)
SELECT 'Test 3', null, null;

PRINT 'Show Table';
SELECT * FROM #Quantities;

DROP TABLE #Quantities