YOU SAID:
he has 20 watermellons
INTO JAPANESE
彼は20ウォーターメロン持っている
BACK INTO ENGLISH
He has 20 water melons
INTO JAPANESE
彼は20の水メロンを持っています
BACK INTO ENGLISH
He has twenty water melons
INTO JAPANESE
彼は20の水メロンを持っています
BACK INTO ENGLISH
He has twenty water melons
Come on, you can do better than that.