Bài 1:
#include<stdio.h>
#include<conio.h>
void main()
{
int a,b,i,j;
printf("nhap vao canh a,b:");
scanf("%d%d",&a,&b);
{
for(i=1;i<=a;i++)
{
for(j=1;j<=b;j++)
printf("*");
printf("\n");
}
}
getch();
}
//ve hinh chu nhat
Bài 2:
#include<stdio.h>
#include<conio.h>
#include<math.h>
void main()
{
int n;
printf("nhap vao n:");
scanf("%d",&n);
int i=0;
int tong=0;
while(i<=n)

{
//int n;
int i;
printf("nhap vao nam:");
//scanf("%d",&n);
scanf("%d",&i);
{
/*for(i=1;i<=n;i++)*/
if(i%4==0 && i%100==0 || i % 400 != 0)
printf("\n so nam nhuan la:%d",i);
}
getch();
}
Bài 5:
#include<stdio.h>
#include<conio.h>
void main()
{
printf("bamg cua chuong");
int i=1;
int j=1;
{
for(i=1;i<=10;i++)
{
for(j=1;j<=10;j++)
printf("\n %d * %d = %d",i,j,i*j);
}
}
getch();
}

void main()
{
int n;
printf("nhap vao gia tri:");
scanf("%d",&n);
int i=1;
int s=0;
{
s=s+(1/i);
i++;
}
printf("tong la:%d",s);
getch();
}
Bài 8:
#include<stdio.h>
#include<conio.h>
void main()
{
int n;
printf("nhap vao gia tri n:");
scanf("%d",&n);
int i=1;
int dem=0;
while (i<=n)
{
n%i==0;
dem=dem+i;
i++;
}

scanf("%d",&n);
int i=1;
int s=0;
while (i<=n)
{
s = s + i;
i++;
}
printf("\n tong la:%d",s);
getch();
}
Bài 11:
#include<iostream.h>
#include<stdio.h>
#include<conio.h>
#include<math.h>
void main()
{
int a,b,c;
float denta,x1,x2;
printf("\n nhap vao a,b,c:");
scanf("%d%d%d",&a,&b,&c);
//float denta,x1,x2;
denta=(float)(b*b)-(4*a*c);
if (denta<0)
printf("phuong trinh vo nghiem");
else
if (denta==0)
{
int x=-b/2*a;

else if(a==b||a==c||b==c)
printf("la tam giac vong can");
else //(a+b>c||a+c>b||b+c>a)
printf("la tam giac thuong");
getch();
}
Bài 13:
//tinh tong s=1^3+2^3+ +n^3
#include<stdio.h>
#include<conio.h>
void main()
int n;
printf("\n nhap vao gia tri n:");
scanf("%d",&n);
int i=1;
int s=0;
while(i<=n)
{
s=s+i*i*i;
i=i+1;
}
printf("\n tong la:%d",s);
getch();
}
Bài 14:
//nhap diem de xem xep loai gi.neu tu 0 den 3 thi yeu,4 kem,5,6thi tb,7,8 kha,9,10 gioi;
#include<stdio.h>
#include<conio.h>
main()
{

scanf("%d",&n);
while (i<=n)
{
s=s+i;
i++;
}
printf("tong la :%d",s);
getch();
}//tinh tong n=1+2+3+ +n
Bài 16:
//su dung ham tinh tong hieu tich thuong cua hai so
#include<stdio.h>
float sohoc(float,float,char);
void main()
{
int a,b;
scanf("%d%d",&a,&b);
printf("nhap vao hai so a,b:");
printf("\n tong la:%f",sohoc(a,b,'+'));
printf("\n hieu la:%f",sohoc(a,b,'-'));
printf("\n tich la:%f",sohoc(a,b,'*'));
printf("\n thuong la:%f",sohoc(a,b,'/'));
}
float sohoc(float x,float y,char tinh)
{
float kq;
switch (tinh)
{
case '+':kq=x+y;break;
case '-':kq=x-y;break;

void main()
{
float r,chuvi,dientich;
printf("nhap vao ban kinh duong tron:");
scanf("%f",&r);
chuvi=(float)2*(pi)*(r);
dientich=(float)(pi)*(r*r);
printf("chu vi la:%.2f\n",chuvi);
printf("dientichla:%.2f\n",dientich);
getch();
}
Bài 19:
#include<stdio.h>
#include<conio.h>
/*{
int n;
int s;
int i;
s=0;
i=0;
printf("nhap vao gia tri n:");
scanf("%d",&n);
while (i<=n)
{
s=s+i;
i++;
}
printf("tong la :%d",s);
getch();}*/
//tinh tong n=1+2+3+ +n