Excel expert needed to finish Excel Calculator tool

Description

We had a freelancer who we've used to make many spreadsheets and calculator tools who has not had time recently to help with turn around projects quickly, so we are looking for another person.
This current project is a calculator tool used for budgeting projects. We need to create validation rules, a few math expressions, and then pivot tables and reports.
We want to be able to have people use this tool without needing to worry about worrying about viruses, so we are not using any macros or vba.
Aside from skill with Excel, the person we select needs to have excellent math skills and be good with large number and data sets.