Question

1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90=?简便运算

1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90=?巧算

Answer 1

1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90
=1/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90
=1/2-1/3+1/3+1/4-1/4-1/5+1/5+1/6-1/6-1/7+1/7+1/8-1/8-1/9+1/9+1/10
=1/2+1/10
=(5+1)/10
=6/10
=3/5

追问

不太懂，能清楚点嘛？草稿算好拍照我看看，谢谢谢谢

追答

1-5/6=1/6=1/2-1/3
7/12=3/12+4/12=1/3+1/4
9/20=4/20+5/20=1/4+1/5
11/30=5/30+6/30=1/5+1/6
13/42=6/42+7/42=1/6+1/7
15/56=7/56+8/56=1/7+1/8
17/72=8/72+9/72=1/8+1/9
19/90=9/90+10/90=1/9+1/10
这样能看明白了吗？