巧算:8+9+10.+199+200
问题描述:
巧算:8+9+10.+199+200
答
8+9+10.+199+200
=1+2+3+……+199+200-1-2-3-4-5-6-7
=(1+200)*200/2-1-2-3-4-5-6-7
=20100-1-2-3-4-5-6-7
=20 072