#include <stdio.h>
   void main()
   {
   
   int first,second;   
   printf("please enter the first number: ");
   scanf("%d", &first);
   printf("%d\n", first+30);
   printf("%d\n", first-3);
   printf("%d\n", first*2);
   printf("%d\n", first/2);
   second=("%d", first/10);
   printf("%d\n", first-second );
   }
C:\Documents and Settings\ול\Desktop>test2.exe
please enter the first number: 10
40
7
20
5
9

#include <stdio.h>
int main(){
    int first=0, second=0;
    printf("Please enter the first number: ");
    if(scanf("%d", &first)!=1)
       return -1;
    printf("%d\n%d\n%d\n%d\n%d\n", first+30, first-3, first*2,\
                                   first/2, first-first/10);
    return 0;
}