This is the 546th most frequent Japanese word.
計
"計" means "plan," "measure," or "calculate."
計 refers to 'plan' or 'planning', used in '計画'.
計画を立てることが大切です。
It is important to make a plan.
計 refers to 'calculation' or 'sum', used in '合計'.
合計は500円です。
The total is 500 yen.
計 refers to 'measure or time', used in '時計'.