20-19-18-17-16-15-14-13-12-11-10-9-8-7-6-5-4-3-2-1 用简便方法计算上面一题
问题描述:
20-19-18-17-16-15-14-13-12-11-10-9-8-7-6-5-4-3-2-1 用简便方法计算上面一题
答
20-19-18-17-16-15-14-13-12-11-10-9-8-7-6-5-4-3-2-1
=20-[(19+1)*9+10]
=20-190
=-170