Help with Multiples program code

I need to create a pseudocode to calculate the sum of the multiples of 4 and 7 between a certain range m and n which will be inputted by the user.

Here is what i tried so far

Begin
Display “Please enter the smaller number in your range”
Input m
Display “Please enter the larger number in your range”
Input n
Incrementor=1
DO
Multiples4=4*incrementor
Multiples7=7*incrementor
IF Multiple4 <=n AND >=m
Sum=Sum+Multiples4
Endif
IF Multiples7 <=n AND >=m
Sum=Sum+Multiples7
Endif
Incrementor=incrementor+1
WHILE Multiples4 and Multiples7 <=n


It's just a snipped but There are many problems with this as you can see. A friend of mine was suggesting divide by the number and then check to see if there is a remainder instead or something. I need some help. Please suggest a method

Hi ! I gave one example may be it will help you.

//Find the sum of all the multiples of 4 or 7 below 1000.
#include<stdio.h>
#include<conio.h>
void main ()
{
int a,b,i,iSum=0;
clrscr();
for (i=1;i<1000;i++)
{
a = i%4;
b = i%7;
if(a==0||b==0)
{
iSum += i;
}


}
printf("\nThe sum of all the multiples of 4 or 7 below 1000: %d\n", iSum);
getch();

}