## C program to multiply two numbers using plus or addition operator:

In this post, we will learn how to *multiply* two numbers by using *plus* or *addition operator*. We will not use the multiplication operator ***, but instead we will use *+*.

For example, if we are multiplying two numbers *4* and *3*, we are actually adding *4* for *3* times or *3* for *4* times.

i.e. *4*3* is equal to *4 + 4 + 4* or *3 + 3 + 3 + 3*.

To do this programmatically, you need to use a loop. The loop will keep adding the number repeatedly to find the result. We will also take the numbers as inputs from the user.

With this program, you will learn *how to take user inputs*, how to use *loops*, how to use the *addition operator* to find out the multiplication and how to print data to the user.

### Algorithm:

We will use the below algorithm:

- Take the numbers as inputs from the user.
- Run one
*loop*for the smaller number of times. We will run it for smaller number of times to make the loop smaller. For example, if we are multiplying*2*with*1000*, the loop will run for*2*times, not*1000*times. - Initialize one variable as
*0*to hold the final multiplication. - Inside the loop, keep adding the other variable to the
*multiplication*variable. - Once the loop is completed, print out the result.

### C program:

Below is the complete C program:

```
#include <stdio.h>
int main()
{
int first, second, i;
int smaller, bigger;
int multiplication = 0;
printf("Enter the first number: ");
scanf("%d", &first);
printf("Enter the second number: ");
scanf("%d", &second);
if (first != 0 || second != 0)
{
if (first < second)
{
smaller = first;
bigger = second;
}
else
{
smaller = second;
bigger = first;
}
for (i = 0; i < smaller; i++)
{
multiplication += bigger;
}
}
printf("Multiplication: %d\n", multiplication);
return 0;
}
```

### Explanation:

Here,

*first*and*second*are two integer variables to hold the first and the second numbers.*i*is initialized to use in the loop.*smaller*and*bigger*are two integer variables to hold the smaller and larger values.*multiplication*is to hold the final multiplication.- If any of these number is
*0*, it will not try to find anything, because the multiplication will be zero. - It is reading the numbers as inputs from the user. The
*if-else*block is finding the smaller and larger number among these two integers. - The
*for loop*is finding the multiplication by adding the bigger value to the*multiplication*variable. - Once the loop is complete, it prints the
*multiplication*value.

### Sample output:

If you run this program, it will print output as like below:

```
Enter the first number: 2
Enter the second number: 2000
Sum: 4000
Enter the first number: 10
Enter the second number: 2345
Sum: 23450
Enter the first number: 1234
Enter the second number: 0
Sum: 0
```

### C program example to find the multiplication using plus with a while loop:

The above program uses a *for loop*. We can also use a *while loop* to find the *multiplication*.

For example:

```
#include <stdio.h>
int main()
{
int first, second, i = 0;
int smaller, bigger;
int multiplication = 0;
printf("Enter the first number: ");
scanf("%d", &first);
printf("Enter the second number: ");
scanf("%d", &second);
if (first != 0 || second != 0)
{
if (first < second)
{
smaller = first;
bigger = second;
}
else
{
smaller = second;
bigger = first;
}
while (i < smaller)
{
multiplication += bigger;
i++;
}
}
printf("Multiplication: %d\n", multiplication);
return 0;
}
```

This example uses a *while loop*. The loop runs until the value of *i* is smaller than the *smaller* number. Inside the loop, we are adding the *bigger* number to the final result value. This part is similar to the previous example.

If you run this program, it will print similar output.

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