Bai 1: cho day so 1,5,9,13,...
a) chu so thu 135 la chu so nao
b) tinh tong 200 so hang dau tien cua day
bai 2: 1/3,11/3,7,31/3,...
a) xac dinh so hang thu 2009 cua day da cho
b) trong 2009 so hang dau tien cua day co ? so tu nhien tinh tong tat ca cac so tu nhien do
cho day so 1,2,3,4,5,6,...1991,1992,day so tren co bao nhieu so hang tinh tong cua cac so hang do
-tong cua so hang thu nhat va thu hai hon so hang dau la 30.
-tong cua 3 so do hon tong 2 so hang dau la 46
-so hang thu nhat bang nua tong 2 so hang con lai
tim so co 3 chu so. Biet trung binh cong cua 3 chu so la 2 va chu so hang tram bang tong chu so hang chuc va hang don vi. Tim 3 chu so do ?
tim so co ba chu so biet rang neu doi chu so hang tram va don vi cua no cho nhau thi gia tri cua no khong thay doi con chu so hang chuc bang mot phan ba tong hai chu so kia
cho mot so co hang don vi la 3 . neu xoa chu so 3 do ta duoc so moi. biet tong cua so moi voi so da cho la 135. tim so da cho
Cho mot phet cong cong co so hang thu nhat hon so hang thu hai la 15 don vi .Biet tong cua so hang thu nhat so hang thu hai va tong bang 682. Tim so hang thu hai cua tong
Tim so co hai chu so, biet chu so hang don vi hon chu so hang chuc la 3, tong cua so phai tim va so viet theo thu tu nguoc lai cua so do bang 143
cho hai so tu nhien co tong bang 8852. tim so be biet rang neu xoa chu so 7 o hang nghin cua so lon thi duoc so be. so be la