tim so tu nhien co 3 chu so , biet rang no tang gap n lan neu cong moi chu so cua no voi n (nla so tu nhien, co the gom mot hay nhieu chu so)
1. tim so tu nhien co 3 chu so,biet so do gap 20 lan tong cac chu so cua no
2. tim so tu nhien co 2 chu so, biet rang neu lay so do chia cho hieu cua chu so hang chuc va hang don vi, thi ta duoc thuong la 28 du 1
3. tim 1 so tu nhien co ba chu so , biet rang neu chuyen chu so cuoi len truoc chu so dau ta duoc so moi hon so da cho 765 don vi
tim so tu nhien co hai chu so, biet rang neu viet them mot chu so 2 vao ben phai va mot chu so 2 vao ben trai cua no thi so ay tang gap 36 lan
tim mot so tu nhien co 2 chu so , biet rang neu viet them mot chu so 2 ao ben phai va mot chu so 2 vao ben ai cua no thi so ay tang gap 36 lan
tim so tu nhien co 2 chu so biet rang neu viet chinh so do xen vao giua hai chu so cua no thi so do tang len 99 lan
tim so tu nhien co 3 chu so biet so do gap len N lan khi ta cong cac chu so cua so do voi N(Nthuoc n)
1.Cho so N la so co hai chu so chia het cho 3.Neu viet xen so 0 vao giua hai chu so do roi cong no voi hai lan chu so hang chuc cua so N ta duoc so moi gap 9 lan so N.Tim so do
2.Tong hai so thap phan la 60,1.Neu dich dau phay cua so nho sang ben phai mot hang roi dem tru di so lon thi ta duoc 219,52.Tim hai so do.
3.Tim so co hai chu so biet neu ta them so 33 vao giua hai chu so do thi duoc mot so moi gap so phai tim 89 lan.
tim so tu nhien co 3 chu so ,biet rang so do gap 20 lan tong cac chu so cua no
tim so chinh phuong n co ba chu so biet rang n chia het cho 5 va neu nhan n voi 2 thi tong cac chu so cua no khong doi