# Practice questions on Loops

## Level 1

1.
Print multiplication table of 24, 50 and 29 using loop.
```#include<iostream>
using namespace std;
int main()
{
for(int i=1;i<=10;i++)
{
cout<<"24 * "<<i<<"\t=\t"<<24*i<<"\n";
}
return 0;
}
```

2.
Take 10 integers from keyboard using loop and print their average value on the screen.
```#include<iostream>
using namespace std;
int main()
{
int sum = 0;
for(int i=0; i<10; i++)
{
int x;
cout << "Enter a number\n";
cin>>x;
sum = sum+x;
}
cout << "The average value is "<<sum/10.0<<"\n";
return 0;
}
```

3.
Print the following patterns using loop :
a.
*
**
***
****
b.
*
***
*****
***
*
c.
1010101
10101
101
1
```#include <iostream>
int main()
{
using namespace std;
int i,j;
for (j=1;j<=4;j++){
for (i=1;i<=j;i++){
cout << "*";
}
cout << "\n";
}
return 0;
}
```

4.
Print ASCII values and their equivalent characters. ASCII value vary from 0 to 255.
```#include<iostream>
using namespace std;
int main()
{
char c;
for(int i=0;i<=255;i++)
{
c = i;
cout<<c<<"\n";
}
return 0;
}
```

5.
Factorial of any number n is represented by n! and is equal to 1*2*3*....*(n-1)*n. E.g.-
4! = 1*2*3*4 = 24
3! = 3*2*1 = 6
2! = 2*1 = 2
Also,
1! = 1
0! = 0
Write a C++ program to calculate factorial of a number.
```#include <iostream>
int main()
{
using namespace std;
int j,number;
cout << "Enter number" << "\n";
cin >> number;
int fact = 1;
for (j=1;j<=number;j++){
fact = fact*j;
}
cout << fact << "\n";
return 0;
}
```

6.
Write a program to find greatest common divisor (GCD) or highest common factor (HCF) of given two numbers.
```#include<iostream>
using namespace std;
int main()
{
int x,y,gcd,lcm,t,b,a;
cout<<"Enter two integers\n";
cin>>x;
cin>>y;
a = x;
b = y;
while(b!=0)
{
t = b;
b = a%b;
a = t;
}
gcd = a;
lcm = (x*y)/gcd;
cout << "GCD is "<<gcd<<" and LCM is "<<lcm<<"\n";
return 0;
}
```

7.
Take integer inputs from user until he/she presses q ( Ask to press q to quit after every integer input ). Print average and product of all numbers.

8.
Write an infinite loop.
A inifinte loop never ends. Condition is always true.

## Level 2

1.
Take as input a fraction in the form a/b. Convert the same into lowest terms and print. (Lowest terms examples 3/12 = 1/4).

2.
Calculate the sum of digits of a number given by user. E.g.-
INUPT : 123        OUPUT : 6
INUPT : 12345        OUPUT : 15

3.
A three digit number is called Armstrong number if sum of cube of its digit is equal to number itself.
E.g.- 153 is an Armstrong number because (13)+(53)+(33) = 153.
Write all Armstrong numbers between 100 to 500.
```#include<iostream>
using namespace std;
int main()
{
for(int i=0;i<500;i++)
{
int sum = 0;
int t = i;
while(t!=0)
{
sum = sum+((t%10)*(t%10)*(t%10));
t = t/10;
}
if(sum == i)
{
cout << i <<"\n";
}
}
return 0;
}
```

4.
Write a program to print all prime number in between 1 to 100.

5.
Write a program to find prime factor of a number.
If a factor of a number is prime number then it is its prime factor.
```#include<iostream>
using namespace std;
int main()
{
int x;
cout<<"Enter the number\n";
cin>>x;

cout<<"Prime factors of "<<x<<" are:\n";

for(int i=2;i<=x;i++)
{
//checking for factor
if(x%i==0)
{
//checking if i is prime or not
int p = 0;
for(int j=2;j<i;j++)
{
if(i%j==0)
{
//i is not prime
p++;
break;
}
}
if(p==0)
{
//if p is 0
//then i is prime
cout<<i<<"\n";
}
}
}
return 0;
}
```

6.
Write a program to find the sum of the even and odd digits of the number which is given as input.