Tinh tong cac chu so cua A biet rang

\(\sqrt{A}=999...96 \) (100 chu so 9).

cho m=999...99 (100 chu so 9) va n=777....77(100 chu so 7) tinh tong cac chu so cua m nhan n

hay chia cac tren mat dong ho lam 2 nhom nhom 1 gom cac so tu nhie lien tiep va nhom 2 gom cac so con lai sao cho :

a) tong cac so cua nhom 1 bang tong cac chu so cua nhom 2

b) tong cac chu so cua nhom 1 bang tong cac chu so cua nhom 2

c) tong cac chu so cua nhom 1 bang 1 nua tong cac chu so cua nhom 2

A=1 2 3...9 10 11...100

Tinh tong cac chu so cua A

cho day so 1,2,3,...,999.tinh tong cac chu so cua day so do

Bai 1 : Cho 3 chu so a ;b ;c thoa man  0< a < b < c. Goi A la tap hop cac so tu nhien co 3 chu so moi so gom ca 3 chu so a, b , c .Biet rang tong cua 2 so nho nhat trg tap hop A =488. Khi do a+b+c=

Bai 2 : Chia cac so tu nhien tu 1 den 100 thanh 2 lop : lop so chan va lop so le .Nhu vay tong cac chu so cua 2 lop hon kem  nhau bao nhieu don vi

Tim so tu nhien co 2 chu so biet rang

a. So do gap 6 lan tong cac chu so cua no

b. So do gap 7 lan tong cac chu so cua no

c. So do gap 8 lan tong cac chu so cua no

d. So do gap 9 lan tong cac chu so cua no

tinh tong cua cac so gom 3 chu so co tan cung la 5

Cho A=671x99...997+2015[thua so 99...997co tat ca 99 chu so 9]Tinh tong cac chu so cua A