YOU SAID:
Stella dropped her cellar phone down seven flights of stairs
INTO JAPANESE
ステラはセラーの電話を7段の階段に落としました
BACK INTO ENGLISH
Stella dropped the cellar's phone on seven steps
INTO JAPANESE
ステラはセラーの電話を7つのステップで落としました
BACK INTO ENGLISH
Stella dropped the seller's phone in 7 steps
INTO JAPANESE
ステラは7つのステップで売り手の電話を落としました
BACK INTO ENGLISH
Stella dropped the seller's phone in 7 steps
That didn't even make that much sense in English.