C Program to Find All Factors of a Number using For Loop

  • Write a C program to print all factors of a number.

Required Knowledge

A number N is a factor of number M, if and only if N divides M completely leaving no remainder(M % N = 0). For example, 4 is a factor of 40 because 4 divides 40 without leaving any remainder.
40 / 4 = 10. and 40 % 4 = 0;
Here is the list of all factors of 40 : 1 2 4 5 8 10 20 40

Algorithm to find all factors of a number N
Check with every number from 1 to N, whether it divides N completely or not.
Let, i be any number between 1 to N
  • If(N % i == 0), then i is a factor of N
  • If(N % i != 0), then i is not a factor of N

C program to find all factors of a number using for loop

#include <stdio.h>  
  
int main() {  
    int counter, N;   
    /* 
     * Take a number as input from user 
     */  
    printf("Enter a Number\n");  
    scanf("%d", &N);  
  
    printf("Factors of %d\n", N);  
    
    /*Check for every number between 1 to N, 
   whether it divides N */
    for(counter = 1; counter <= N; counter++) {   
        if(N%counter == 0) {  
            printf("%d ", counter);  
        }  
    }  
  
    return 0;  
}

Output
Enter a Number
40
Factors of 40
1 2 4 5 8 10 20 40
Enter a Number
37
Factors of 37
1 37
Write a C program to find product of digits of a number using while loop.
Wap in C to multiply the digits of a number.

Required Knowledge

To multiply digits of a number we have to remove one digit at a time, we can use '/' division and '%' modulus operator. Number%10 will give the least significant digit of the number, we will use it to get one digit of number at a time. To remove last least significant digit from number we will divide number by 10.

Product of digits of 2534 = 2 x 5 x 3 x 4 = 120

Algorithm to find product of digits of a number
  • Get least significant digit of number (number%10) and multiply it to the product variable.
  • Remove least significant digit form number (number = number/10).
  • Repeat above two steps, till number is not equal to zero.

C program to find sum of all even numbers between 1 to N using for loop

#include <stdio.h>
#include <conio.h>  
  
int main() {  
    int num, temp;  
    long productOfDigit = 1;  
  
    /* 
     * Take a number as input from user
     */  
    printf("Enter a Number\n");  
    scanf("%d", &num);  
    temp = num;
    
    while(num != 0){
        /* get the least significant digit(last digit) 
         of number and multiply it to productofDigit */
        productOfDigit *= num % 10;
        /* remove least significant digit(last digit)
         form number */
        num = num/10;
    } 
  
    printf("Product of digits of %d = %ld", temp, productOfDigit);  
  
    getch();
    return 0;  
}

Output
Enter a Number
2436
Product of digits of 2436 = 144
Enter a Number
2222
Product of digits of 2436 = 16

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