# C Exercises: Sum of all the multiples of 3 or 7 below 100

## C Programming Challenges: Exercise-17 with Solution

The natural numbers below 10 that are multiples of 3 or 7 are 3, 7, 6 and 9. The sum of these multiples is 25.

Write a C programming to find the sum of all the multiples of 3 or 7 below 100.

**C Code:**

```
#include <stdio.h>
int main(void)
{
int sum3 = 0, sum7 = 0, sum21 = 0;
int i;
for (i = 0; i < 100; i++) {
if (i % 3 == 0) {
sum3 += i;
}
if (i % 7 == 0) {
sum7 += i;
}
if (i % 21 == 0) {
sum21 += i;
}
}
printf("%d\n", sum3 + sum7 - sum21);
return 0;
}
```

Sample Output:

2208

**Flowchart:**

## C Programming Code Editor:

** Contribute your code and comments through Disqus.**

**Previous C Programming Exercise:** Length, longest valid parentheses substring.

**Next C Programming Exercise:** Sum even-valued in a Fibonacci sequence.

**What is the difficulty level of this exercise?**

Test your Programming skills with w3resource's quiz.

**Weekly Trends and Language Statistics**- Weekly Trends and Language Statistics