>>>You can see my solution in the thread I mentioned to Tore - I also first need to convert to decimal and make a pick on the precision. I chose 11 digits as using higher precision changes the original number (as it was float 0.99 it will become 0.98000089, something like that).
>>
>>Find the number of decimal of a float is a waste of time,
>>because a solution does not exist.
>>Some floats have an infinite number of decimal places,
>>so we must first convert them into decimals.
>>At this point the problem becomes to find the number of decimal places of a decimal ...
>
>I agree. So, how do you find a number of decimal places of a decimal?

1. you design the db then you known
2. COLUMNPROPERTY(..,'SCALE')
3.

-- this work with 1 or more decimals
select	CHARINDEX('.',REVERSE(NULLIF(CAST(Value % 1 as varchar(40)))))-1
-- with 0 decimals, CASE WHEN Value % 1=0 THEN 0 ...