4/7 cua 1 so la 20 thi so do la so nao

mot so co hai chu so biet tong cac chu so cua no la 8 hieu cac chu so cua cua no la 4 va chu so hang chuc lon hon hang don vi so do la so nao

cho 100 so huu ti trong do tich cua bat ki ba so nao cung la mot so am, chung minh rang:

a) tich cua 100 so do la mot so duong

b) tat ca 100 so do deu la so am

tìm tất cả các số tự nhiên ma khi ta gach bo mot chu so nao do cua so do thi duoc so moi nho hon so cu la 2013 don vi

dien dung sai

a/tich cua hai so nguyen duong la mot so nguyen duong

b/tich cua hai so nguyen am la mot so nguyen am

c/tich cua 2 so nguyen cung dau luon lon hon moi so do

d/tich cua hai so nguyen khac dau luon nho hon moi so do

e/neu tich hai so nguyen la mot so nguyen duong thi hai so do deu la so nguyen duong

f/neu tich hai so nguyen la mot so nguyen am thi hai so do deu la so nguyen am

Cho 61 so nguyen .Hoi tong cua 61 so nguyen do la so nhu the nao neu :

a,Tong cua 6 so bat ki trong chung la mot so nguyen am 

b, tong cua 6 so bat ki trong chung la mot so nguyen duong

mot so + mot so=20 . hai so do la so nao 

1/4 cua mot so bang 75 thi so do la?

3/4 cua mot so bang 192 thi so do la?