Math Operations should be able to utilize opportunity.custom_fields. Limiting math operations to only contact.custom_fields is extremely limiting. I can have 1 contact associated with multipe opportunities. With the current limitation I would need to create multiple contacts. This makes zero sense. If I see Contact A, three different products or services that is three different opportunities and shouldn't require 3 duplicate contacts. Especially when we are trying to calculate Monthly Recurring Charge (MRC) multipled by Term Agreement (12, 24, 36, 48, 60 months), and then calculate commissions MRC x Commission % = Monthly Recurring Commissions x Term Agreement and even Sub-Agent Commissions: Monthly Recurring Commissions x Sub Agent Commission % = Sub Agent Monthly Commission. All of this is specific to an Opportunity, NOT a contact.