unsigned long cnt32;
unsigned  int x,y;
x=400;
y=400;

cnt32 = x*y;     编译正常不报警，但运算结果为0x27100的低16位0x7100,而不0x27100

cnt32 = 400*400;     报警提示 integer operation result is out of range

请问，怎样才能得到正确结果.