20 chắc chắn luôn trong violympic lớp 5 vòng 15
nhớ tk m nhé
Ta có dạng :
abcd Dóng theo cột dọc ta thấy a chỉ có thể bằng 1
+ ab b chỉ có thể bằng 9 vì a bằng 1 thay vào thành 1bcd + 1b = 1979
------------- Vậy số phải tìm là 19
1979
Cậu làm sai rồi vì nếu là 20 thì số có 4 chữ số sẽ là 20..... thế thì số hạng lớn hơn tổng à
Cậu 100 % là thi violmypic vòng 15 k được 300 điểm
mà câu này ở trong bài Web tự luận làm sao cậu biết là đúng
20 la dung day hom truoc minh thi huyen 300/300 19 la sai minh chac chan 1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 vo tan %
