It's 20 dollars bud. https://www.amazon.com/Texas-Instruments-TI-30X-Scientific-Calculator/dp/B07G9J7Y3Z/ref=pd_bxgy_img_3/137-9599009-1684259?_encoding=UTF8&pd_rd_i=B07G9J7Y3Z&pd_rd_r=40ac7d05-c14b-4e86-a8f8-726e2832d91c&pd_rd_w=O986P&pd_rd_wg=u1Okh&pf_rd_p=f325d01c-4658-4593-be83-3e12ca663f0e&pf_rd_r=CK2EB1M8RYC911D14NB1&psc=1&refRID=CK2EB1M8RYC911D14NB1
I recall making many, many graphs and matrices by hand.