Bài 1:
/**In ra man hinh tat ca cac hop so <100**/
public class bai05 {
public static void main(String[] args)
{
int k,n,dem;
for(k=1;k<=100;k++)
{
dem=0; // dat ja tri cua bien dem=0 ung voi moi ja tri cua k
for(n=2;n<=k;n++)
{
if(k%n==0) // neu so du khi chia k cho n =0
{
dem++; // thi bien dem duoc cong them 1 don vi
}
}
}
}
if(dem>1)
{
System.out.println("hop so la"+k);
}
}
}
Bài 06
/**In ra man hinh 15 so nguyen to dau tien**/
public class bai06 {
public static void main(String[] args)
{
int k=0,n,dem,j=0;// khai bao cac bien, dat ja tri ban dau cho cac bien can thiet
while (j<15) // trong khi so nguyen to da in < 15
{
k++; // cong cho k 1 don vi
dem=0; // reset gia tri cua bien dem =0 ung voi moi ja tri cua k
for (n=2;n<=k;n++)
{
if (k%n==0)
{
dem++;
}
}
if (dem==1)
{
System.out.print(k+" ");
j++;// so lan in duoc cong them 1
2
}
}
}
}
Kết quả
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47
Process completed.
Bài 07
/**In ra man hinh tat ca cac so nguyen to tu 1000 den 2000**/
public class bai7 {
public static void main(String[] args) {
int k,n,dem;
for (k=1000;k<=2000;k++)
{
dem=0;
for (n=2;n<=k;n++)
{
if(k%n==0)
dem++;
}
if(dem==1)
System.out.println(k);
}
}
}
Bài 08
/**In ra man hinh cac so <100 va chia het cho 3,7*/
public class bai08 {
public static void main(String[] args) {
int k,n;
for (k=1;k<100;k++)
{
if ((k%3==0) && (k%7==0))
System.out.print(k+" ");
}
}
}
Kết quả
21 42 63 84
Process completed.
Bài 09
/**In ra man hinh cac so nam giua 1000 va 200 dong thoi chia het cho 3,5,7*/
public class bai09 {
public static void main(String[] args) {
int k;
for (k=1000;k<=2000;k++)
{
if((k%3==0)&(k%5==0)&(k%7==0))
System.out.print(k+" ");
}
}
}
Kết quả
1050 1155 1260 1365 1470 1575 1680 1785 1890 1995
Process completed.
Bài 10
/**In ra man hinh 5 so hoan hao dau tien( so hoan hao la so co tong bang cac uoc so cua minh ke ca 1)**/
public class bai10 {
public static void main(String[] args) {
int k=0,j=0,n,tong;
while(j<5)
{
k++;
tong=1;// vi 1 luon la uoc cua cac so hang
for(n=2;n<k;n++) //
ja tri ban dau cua n = 2 thay vi dat bang 1 vi da tinh 1 la uoc o phia
tren
{
if (k%n==0)
tong+=n;
}
if (k==tong)
{
System.out.print(k+" ");
j++;
}
}
}
}
Kết quả
1 6 28 496 8128
Process completed.
Bài 11
/*Trong cac so tu nhien <=100 hay dem xem co bao nhiu so
*- Chia het cho 5
*- Chia 5 du 1
*- Chia 5 du 2
*- Chia 5 du 3
*/
public class bai11 {
public static void main(String[] args) {
int dem0,dem1,dem2,dem3;
int d,k;
4
dem0=0;dem1=0;dem2=0;dem3=0;
for (k=5;k<=100;k++)
{
switch(d=k%5)
{
case 0 :
dem0++;
break;
case 1:
dem1++;
break;
case 2:
dem2++;
break;
case 3:
dem3++;
break;
}
}
System.out.println("so cac so chia het cho 5 la:" +dem0);
System.out.println("So cac so chia 5 du 1 la:"+dem1);
System.out.println("So cac so chia 5 du 2 la:"+dem2);
System.out.println("So cac so chia 5 du 3 la:"+dem3);
}
}
Kết quả
so cac so chia het cho 5 la:20
So cac so chia 5 du 1 la:19
So cac so chia 5 du 2 la:19
So cac so chia 5 du 3 la:19
Process completed.
Bài 12
/*** Cho so tu nhien N bat ki( da gan truoc do),tim va in ra uoc so nguyen to nho nhat cua N*/
public class bai12 {
public static void main(String[] args)
{
int N=40;
int k;
for (k=2;k<=N;k++)
{
int dem=0;
for(int x=2;x<=k;x++)
if(k%x==0)
dem++;
if ((N%k==0)&&(dem==1))
{
5
System.out.print("uoc so nguyen to nho nhat la:"+k );
break;
}
}
}
}
Kết quả
uoc so nguyen to nho nhat la:2
Process completed.
Bài 13
/*Cho so tu nhien N > 1 bat ki ( da gan truoc do)
*In ra khai trien thanh tich cac so nguyen to tinh tu nho den lon
*Vd 9--> 3.3
*12--> 2.2.3
*/
//Cách 1: dùng for
public class bai13 {
public static void main(String[] args) {
int N=12;
int k;
for (k=2;k<=N;k++)
{
if (N%k==0)
{
System.out.print(k+" ");
N=N/k;
k--;
}
}
}
}
//Cách 2: dùng while
public class bai13 {
public static void main(String[] args) {
int N=12,k=2;
while(k<=N)
{
for(k=2;k<=N;k++)
{
if (N%k==0)
{
System.out.print(k+" ");
N=N/k;
break;
}
}
}
}
}
Kết quả
2 2 3
6
Process completed.
Bài 14
/**Cho truoc so tu nhien N bat ki (da gan truoc do)
*In ra man hinh tat ca cac uoc so nguyen to khac nhau cua N*/
public class bai14 {
public static void main(String[] args) {
int k,n,dem,N=1027;
for (k=1;k<=N;k++)
{
dem=0;
for (n=2;n<=k;n++)
{
if (k%n==0)
{
dem++;
}
}
if (dem==1 & N%k==0)
{
System.out.print(k+” “);
}
}
}
}
Kết quả
13 79
Process completed.
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