Zoology has 7 letters in total, with O repeated thrice
7!3!\frac{7!}{3!}3!7! → 7⋅6⋅5⋅4⋅3⋅2⋅13⋅2⋅1\frac{7\cdot6\cdot5\cdot4\cdot3\cdot2\cdot1}{3\cdot2\cdot1}3⋅2⋅17⋅6⋅5⋅4⋅3⋅2⋅1
= 840ways
