我是新人。两天看书的成果汇报

#include <stdio.h>
main(void)
{
     float banjin = 0.0f;
     float pi = 3.141592654f;
     float jieguo1 = 0.0f;
     float jieguo2 = 0.0f;
        printf("shu ru banjin");
        scanf("%f",%banjin");
        jieguo1 = banjin * 2 * pi;
        jieguo2 = pi * banjin * banjin;
        printf("zhou chang shi %f \n",jieguo1);
        printf("mian ji shi %f \n",jieguo2);
}
/* 求指正 */