1+2+3+···+86+87+88=?
问题描述:
1+2+3+···+86+87+88=?
答
(1+88)*88*1/2=3916
答
=89*88/2=3916
1+2+3+···+86+87+88=?
(1+88)*88*1/2=3916
=89*88/2=3916