co bao nhieu so tu nhien co 2 chu so sao cho trong moi so co it nhat mot chu so 5
Co bao nhieu so co 5 chu so ma so do chia het cho 3 ,dong thoi co it nhat 1 chu so 6
Tu 1 den 99 co cao nhieu so chau it nhat mot chu so 2
Bai 2 Trong cac so tu nhien co 3 chu so co bao nhieu so
a) CHua dung mot chu so 4
b) Chua dung hai chu so 4
so co dang 1010...10101 chia het cho 9. so d9o co it nhat bao nhieu chu so 1
Co bao nhieu so tu nhien co hai chu so sao cho moi so chu so hang chuc lon hon chu so hang don vi ?
so co dang 1010 ....... 10101 chia het 9999.So do co it nhat bao nhieu chu so 1
voi 2 chu so la ma 1 va 5(so la ma) so la ma lon nhat co the viet dc
(moi chu so co the dung nhieu lan hoac ko dung)
co gia tri tuog ung trog he thap phan la
Cau 1: Co tat ca bao nhieu so co 3 chu so ma trong moi so co duy nhat 1 chu so 5.
Cau 2: Biet rang 3n+1 va 5n+4 (n thuoc N) la hai so khong nguyen to cung nhau. Khi do UCLN cua 3n+1 va 5n+4 la bao nhieu.
Cau 3: Tim cap (x;y) nguyen am thoa man:xy+3x+2y+6=0 va lxl+lyl=5.
co bao nhieu so tu nhien co hai chu so sao cho trong moi so do c/s hang chuc be hon chu so hang dvi