Question

[Con's Trai's Cưng's]

viet so tu nhien N =12345678910111213141516...70 ,

a)so N co bn chu so

,b) cs hang don vi cua so 53 dung hang thu may (ke tu trai sang phai moi cs 1 hang),

c) cs viet o hang thu 120 la cs nao?cs do cua so tn nao

Answer 1

[Nho Bùi]

a) so phan tu n la(70-1):1+1 =70 

Answer 2

[Nguyen Tran Tuan Hung]

a,Tu 1 > 9 co 9 chu so

Tu 10 > 70 co 122 chu so

So N co 9+122=131 chu so