加法: 1+2= 1+3= 1+4= 1+5= 1+6= 1+7= 1+8= 2+2= 2+3= 2+4= 2+5= 2+6= 2+7= 2+8= 3+2= 3+3= 3+4= 3+5= 3+6= 3+7= 4+2= 4+3= 4+4= 4+5= 4+6= 1+9= 5+2= 5+3= 5+4= 5+5= 6+2= 6+3= 6+4= 7+2= 7+3= 8+2= 减法: 9-1= 8-1= 7-1= 6-1= 5-1= 4-1= 3-1= 9-2= 8-2= 7-2= 6-2= 5-2= 4-2= 3-2= 9-3= 8-3= 7-3= 6-3= 5-3= 4-3= 3-3= 9-4= 8-4= 7-4= 6-4= 5-4= 4-4= 9-5= 8-5= 7-5= 6-5= 5-5= 2-1= 9-6= 8-6= 7-6= 6-6= 2-2= 9-7= 8-7= 7-7= 1-1= 9-8= 8-8= 9-9= 本文来源：https://www.wddqw.com/doc/5f0af74ef7ec4afe04a1dfd4.html