63×21+65×37+63×44的巧算=63x（21+44）+65x37=63x65+65x37=（63+37）x65=100x65=6500
63x21+65x37+63x44=(63x21+63x44)+65x37----------此步骤书写时可省略------=63x(21+44)+65x37=63x65+65x37=65x(63+37)=65x100=6500
