"계산기" "숫자 아님" "오류" "cos" "ln" "log" "sin" "tan" "clr" "del" "오일러의 수" "원주율(파이)" "소수점" "왼쪽 괄호" "오른쪽 괄호" "코사인(cosine)" "자연로그" "로그" "사인(sine)" "탄젠트(tangent)" "더하기" "나누기" "팩토리얼" "곱하기" "거듭제곱" "제곱근" "빼기" "지우기" "삭제" "등호"