SQL Server check resultant data type of expression

SQL_VARIANT_PROPERTY is close

DECLARE @what sql_variant;
DECLARE @foo decimal(19,3) = 1, @bar decimal(11,7) = 2;

SELECT @what = @foo / @bar;
SELECT
    SQL_VARIANT_PROPERTY(@what, 'BaseType'),
    SQL_VARIANT_PROPERTY(@what, 'Precision'),
    SQL_VARIANT_PROPERTY(@what, 'Scale'),
    SQL_VARIANT_PROPERTY(@what, 'MaxLength');

SELECT @what = @foo + @bar;
SELECT
    SQL_VARIANT_PROPERTY(@what, 'BaseType'),
    SQL_VARIANT_PROPERTY(@what, 'Precision'),
    SQL_VARIANT_PROPERTY(@what, 'Scale'),
    SQL_VARIANT_PROPERTY(@what, 'MaxLength');


SELECT @what = @foo * @bar;
SELECT
    SQL_VARIANT_PROPERTY(@what, 'BaseType'),
    SQL_VARIANT_PROPERTY(@what, 'Precision'),
    SQL_VARIANT_PROPERTY(@what, 'Scale'),
    SQL_VARIANT_PROPERTY(@what, 'MaxLength');

Or temp table/SELECT..INTO.. as an extension of what you’ve already done

Edit: Remus’ answer?