Question

从1/2,1/3,1/4,1/5到1/99中选出10个相加,等于1

Answer 1

1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/10=1

1=1/2+1/2-1/3+1/3-1/4+1/4.-1/10+1/10

=1/2+(1/2-1/3)+(1/3-1/4).+(1/9-1/10)+1/10

=1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/10