scanf shows number always as pair

The variable N is integer type. But in your scanf call you are using "%f" which is float . Change to "%d" (used for decimal integers) that the reading will be done correctly.

Read about scanf and prinf also, it will help.

See running on ideone .

I took the liberty to make some modifications, I tried to change the minimum possible of your program, first the "% d" of your scanf, you were using "% f" that serves for float, another thing I also used was the modification of the condition of the second if, which went on to compare if the rest of the division is (! =) nonzero (then going to odd numbers and else for the pairs), I also used the translation library to enable the characters of our language. I think that would solve your problem. I leave a piece of advice, it would be nice to use the keys in if, else if and else, to avoid minor confusions, indentation and organization help a lot for the understanding and execution of the program.

#include <stdio.h>
#include <stdlib.h>
#include <locale.h>

int main (){
    setlocale(LC_ALL, "Portuguese");
    int N;
    printf ("Digite um numero: ");
    scanf("%d", &N);
    if (N<0)
            printf ("Este número não é positivo\n\n");
    if(N%2!=0)
        printf ("Este numero e ímpar\n\n");
    else
        printf("Este número é par\n\n");
    system ("PAUSE");
}