tim cac so co sau chu so - biet cac chu so thuoc lop don vi deu la 1 , cac chu so thuoc lop nghin la cac chu so chan khac nhau , khac 0 va nho hon 8.co bao nhieu so ?

- tim so chu so chan co 4 chu so 

- viet tat ca cac so tu 100 den 999phai dung bao nhieu chuvso 9

-co bao nhieu so le co 3 chu so

- viet 1000 sdo tu nyhien dau tien hoi chu so 3 cco mat bao nhieu lan

-viet tap hop cac so tu nhien co 2 chu so trong do a ) chu so hang chuc nho hon hang don vi la 4 b) chu so hang chuc gap 3 lan chu so hang don vi   c) chu so hang chuc nho hon chu so hang don vi ( tong 2 chu so = 12) 

Tong cua 2 so la so tu nhien bang 1092 . Neu o so hang thu nhat lan luot thay chu so hang don vi la 9 thanh 3 ,that chu so hang chuc la 7 thanh 1 thi duoc so hang thu hai .Tim hai so do ? ming cac ban giup minh giai bai toan nay nhe va nho co ca loi giai nha cac ban nhe ?

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

cho h la tap hop cac so tu nhien co hai chu so ma chu so hang chuc gap 3 lan chu so hang don vi phan tu nho nhat cua tap hop h la

tong cac chu so cua mot so co 2 chu so bang so tu nhien nho nhat co 2 chu so va chu so hang chuc gap 4 lan chu so hang don vi do la so nao ?

( ghi them loi giai )

cho E tap hop cac so tu nhien co hai chu so ma hu so hang chuc nho hon chu so hang don vi la 4 ,tim so tap hop g

tim 3 so tu nhien lien tiep trong do so nho la chan va mot trong 3 so do co mot so chia het cho 9, biet tong 3 so do la mot so co 3 chu so co cac dac diem sau: chia het cho 5,tong chu so hang tram va hang don vichia het cho9, chu so hang chuc la chan

cho G la tap hop cac so tu nhien co 2 chu so ma chu so hang chuc nho hon chu so hang don vi la 6. Số phần tử của tập hợp G