Bai 1 :Tim so tu nhien co 6 chu so biet chu so hang don vi la 4 va neu chuyen chu so do len hang dau tien thi so do tang gap 4 lan.

Bai 2:Cho 3 chu so a,b,c sao cho 0<a<b<c.

a]Viet tap hop cac so tu nhien co 3 chu so gom ca 3 chu so a,b,c.

b]Biet tong 2 so nho nhat trong tap A=488.Tim 3 chu so A,B,C.
 

tim cac chu so a,b,c biet: 0,a+a,b+ab,c=bc,b ( cac chu so khac nhau bieu dien cac chu so khac nhau)

1,

Cho a=2^13.5^7 . Tim so cac chu so cua so a

2 , 

Cho b=3^2009.7^2010.13^2011 . Tim chu so hang don vi cua b

Cho 3 chu so a,b,c voi 0<a<b<c

a,Viet tap hop A cac so co 3 chu so,moi so gom ca 3 chu so tren

b, Biet tong 2 chu so nho nhat trong tap hop A=499. Tim tong cac chu so a+b+c

Voi bon chu so a,b,1,2 ban Thuy viet duoc 18 so co ba chu so . Khi tinh tong cua cac chu so da viet duoc 6440. tim chu so a,b.

cho A la mot so co hai chu so ,B la tong cac chu so cua A .C la tong cac chua so cua B .tim A biet A=B+C+44

cho ba chu so a,b,c voi 0<a<b<c

a) viet tap hop A cac so co 3 chu so, moi so gom ca ba chu so tren

b) biet rang tong 2 so nho nhat trong tap hop A bang 499.tim tong cac chu so a+b+c

Bai1:cmr 2 stn dang 2n+3 va 3n+2 bao gio cung la 2 so nguyen to cung nhau.

Bai 2:tim 2 chu so a ; b biet (a+b)(a-b)=20.

Bai 3: tim 2 stn lien tiep co 2 chu so sao cho 1 so chia het cho 25, so kia chia het cho 4.

Bai 4: tim a;b biet a.b=360 va BCNN(a,b)=60

cho 3 chu so a,b,c, thoa man :0<a<b<c

a/viet tap hop A cac so tu nhien co ba chu so gom ca ba chu so a,b,c.

b/biet tong hai so nho nhat trong tap A bang 488. Tim 3 chu so a,b,c noi tren