pronunciation quirk that I'm not sure how common it is or if it's scoped to a particular academic tradition:

arithmetic as uh-RITH-muh-tick /ʌ.ˈɹɪθ.mə.tɪk/ = the branch of applied mathematical calculation

arithmetic as aa-rith-MEH-tick /æ.ɹɪθ.ˈmɛ.tɪk/ = the adjective for above