so sau la so nguyen to hay hop so

A=111111111...11(2016 chu so 1)

B=1010101

C=1112111 

Ban nao dung minh se tich

Bai 1Tim nguyen to a de 4a+11 la so nguyen to nho hon 30

Bai 2 cac so sau la so nguyen to hay so hop so:

a=1*3*5*7*....*13+20

b=147*247*347-13

1,cac so sau la so nguyen to hay hop so

a,E=1!+2!+3!+.............+100!

b,G=3.5.7.9-28

c,H=311141111

cac so sau la so nguyen to hay hop so:

a)a=1.3.5.7.13+20

b)b=147.247.347-1

a, tim so tu  nhien trong khoang tu 100 den 300 biet rang so do chia cho 4 cho 5 cho 6 deu du 2 nhung so do lai chia het cho 11

b, dung ba chu so 1 ; 2 ; 3 hay viet tat ca cac so tu n hien co ba chu so ma cac chu so khac nhau , chung to rang tat ca cac so tu nhien do dau la hop so

c, tim so tu nhien nho nhat cho bon chu so giong nhau biet rang so do co dung ba uoc deu la o nguyen to

Cho A= 2222.....22000...000111...11(co 100 chu so 2, 100 chu so 0 , 100 chu so 1 )

Hoi A la so nguyen to hay hop so ? taisao?

Các số sau là số nguyên tố hay hợp số:

a) A= 11...1(2001 chữ số 1)

b) B= 11...1(2000 chữ số 1)

c) C=1010101

d) D= 1112111

e) E= 1!+2!+3!+...+100!

g) G= 3.5.7.9-28

Bai 1:tim so nguyen P biet P+2va P+4 deu la nguyen to

bai 2: tong 2^100×7×11+81^3  la nguen to hay hop so ( giai thich)

Bai 3: tim so nguyen to P de P +2,p+6,P+8 deu la cac so nguyen to

1)Viet tap hop B gom can so la tich cua dung 3 so Nguyen to co 1 chu so 

2) Viet tap hop A gom cac so chan co 4 chu so va co tich cac chu so bang 10