tim tat cac so tu nhien co ba chu so thoan man cac tinh chat sau : co tong cac chu so bang 9 chu so hang chuc lom hon chu so hang don vi la 2 don vi va neu ta doi chu so hang tram cho hang don vi thi duoc so moi lon hon so ban dau la 198 don vi

Tim so tu nhien co 2 chu so biet rang chu so hang chuc lon hon chu so hang don vi la 2 va so do lon hon tong cac binh phuong cac chu so cua no la 1.

viet tap hop cac so tu nhien co hai chu so,trong do:

a,chu so hang don vi lon hon chu so hang chuc 4 don vi

b,chu so hang don vi gap 3 lan chu so hang chuc

c,chu so hang don vi nho hon chu so hang chuc va tong hai chu so =17

tim so co 3 chu so biet chu so hang tram nho hon chu so hang chuc,chu so hang chuc nho hon chu so hang don vi va tong cac chu so do bang 6

tim so co 3 chu so lon nhat co cac chu so khac nhau ma cac chu so hang don vi bang trung binh cong cua chu so hang tram va chu so hang chuc . tim so do

Viet tap hop cac so tu nhien co hai chu so,trong do:

a) Chu so hang chuc nho hon chu so hang don vi la 5

b) Chu so hang chuc gap 4 lan chu so hang don vi

c) Chu so hang chuc nho hon chu so hang don vi, tong hai chu so bang 14

tim 1 so tu nhien lon nhat co 3 chu so khac nhau ma ti so giua chu so hang tram va chu so hang chuc = ti so giua chu so hang chuc va hang don vi

viet bang cah liet ke cac phan tu cua cac tap hop sau:

a) tap hop A cac so tu nhien co 2chu so ma chu so hang chuc lon hon chu so 3 

b) tap hop B cac so tu nhien co 2 chu so ma chu so hang don vi gap doi hang chuc 

c) tap hop C cac so tu nhien co 2 chu so ma trong so do co it nhat 1 chu so 4 

Tong cac chu so cua so tu nhien co 3 chu so la 12. Chu so hang chuc bang tong chu so hang tram va hang don vi. Neu doi vi tri chu so hang tram va hang don vi thi duoc so moi hon so cu la 396. Tim so ban dau.

                       (giải ra)