Cho: A,B trong do Agom 2m chu so 1 , B gom m chu so 4
Chung minh rang A+B+C+1 la so chinh phuong
Tim so chinh phuong co 4 chu so sao cho khi bot moi chu so di 1 don vi ta cung duoc so chinh phuong
cho 1 so chinh phuong co 4 chu so. Biet rang chu so tan cung cua no la so nguyen to, tong cac chu so cua no cung la so chinh phuong va can bac 2 cua no co tong cac chu so cung la so chinh phuong
tim mot so co 3 chu so biet rang neu tang chu so hang tram them n don vi giam chu so hang chuc va don vi di n don vi ta duoc 1 so co 3 chu so gapn lan chu so ban dau
Tim mot so chan lon nhat co 5 chu so ma 3 chu so dau giu nguyen gia tri tu trai sang phai tao thanh mot so chinh phuong va 3 chu so cuoi giu nguyen thu tu tao thanh 1 lap phuong dung
cho 1 so co 2 chu so biet khi ta bo chu so hang don vi cua so lon thi ta duoc so be va so lon bang 10 lan so be. Tim 2 so do
Tim so tu nhien n co hai chu so biet rang hai so (2n+1) va (3n+1) dong thoi la so chinh phuong.
tim abcd gom 4 chu so sao cho abcd=(5c+1)2
cho 15 so tu nhien khac nhau va khac 0,trong do moi so khong lon hon 28.Chung to rang trong 15 so da cho bao gio cung tim duoc it nhat 1 nhom co 3 so ma so nay bang tong 2 so con lai hoac 1 nhom gom 2 so ma so nay gap doi so con lai