Question

1-100之内的取十位数字的倒数,正负自取,和为负1,这十个数是多少?

Answer 1

-2、-3、+4、-6、-12、-16、-24、-32、-48、-96

-1/2-1/3+1/4-1/6-1/12-1/16-1/24-1/32-1/48-1/96

=-48/96-32/96+24/96-16/96-8/96-6/96-4/96-3/96-2/96-1/96

=-（48+32-24+16+8+6+4+3+2+1）/96

=-96/96=-1