几道数学题,(简便方法）
问题描述：
几道数学题,(简便方法）
654321X123456-654322X123455
8642X2468-8644X2466
2002X60066006-3003X40044004
1234X432143214321-4321X123412341234
50X96+57X4+7X66
9999X1222-3333X666
1989X1999-1988X2000
7654321X124567-77654322X1234566
答
654321X123456-654322X123455=654321X123456-（654321+1)X(123456-1)=654321X123456-654321X123456-123456+654321+1=530866
8642X2468-8644X2466=8642X2468-(8642+2)X(2468-2)=8642X2468-8642X2468-2X2468+2X8642+4=2X(8642-2468)+4=12352
2002X60066006-3003X40044004=2X1001X6X10011001-3X1001X4X10011001=0
1234X432143214321-4321X123412341234=1234X4321X100010001-4321X1234X100010001=0