Use Lookup Field in Report - Text Only?

Use Lookup Field in Report - Text Only?

I have a Form A with a decimal field that I am using to create a dropdown list as a lookup in another Form B.

Using form B the user can select from a list of available numbers from records in Form A.

I need to generate a report that shows the sum of the numbers for each record in form B.

When I go to create the report, the lookup field in Form B shows up as text, not the looked up decimal field.  I am unable to sum the lookup field even though the field is linked to a decimal.  Is this a limitation or am I doing something wrong?