Do I need to pay tax if I am working freelance and earn about $2000 annually?

I’ve been working freelance for a math company to provide solutions and i was wondering if i need to file a tax form. And if i do, how much will i need to pay each year?
Since the only thing i use for the job is a calculator and couple math textbooks, I dont think I can deduct these expenses from the taxes. If this is the case, how much will i need to pay for an self-employment of $ 2000?