1/2=1/1*2=1-1/2
1/6=1/2*3=1/2-1/3
………………
1/56=1/7*8=1/7-1/8
解
原式
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+……+(1/7-1/8)
=1+(1/2-1/2)+(1/3-1/3)+……+(1/7-1/7)-1/8
=1-1/8
=7/8
1/2=1/1*2=1-1/2
1/6=1/2*3=1/2-1/3
………………
1/56=1/7*8=1/7-1/8
解
原式
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+……+(1/7-1/8)
=1+(1/2-1/2)+(1/3-1/3)+……+(1/7-1/7)-1/8
=1-1/8
=7/8